Volt Axial

is there any axial lead rectifier to work on 15 amp 15 volt DC?

is there any axial lead rectifier to work on 15 amp 15 volt DC what is its number and rating electronics

Not sure about your “axial lead” comment. You can connect wires on the thing if it has terminals instead.

http://www.radioshack.com/product/index.jsp?productId=2062584&cp=&sr=1&origkw=rectifier&kw=rectifier&parentPage=search

So long as the voltage and current ratings are equal or greater then anything is fine for a rectifier.

Saints defensive mechanism

Defensive mechanism of the SS

Circuit Breaker:

I. Introduction

The main functions of a circuit breaker interrupts the short circuit current, carrying currents normal, normal OFF docking and charging, and providing the necessary insulation between live parts and ground parts. The problems involved with maintaining the bulk oil circuit switches were immense. Minimum oil technology had replaced the bulk oil technology during 1950. Similarly, the air blast technology was developed to obtain higher performance characteristics. However, air-jet switches are quite expensive and their operation and maintenance difficulty. As both, and felt the need during 1960 reduced maintenance.

SF6 was obtained first fluoride and sulfur in 1900 by M / s. H. MOSS and PLEBEAU. Behavior of SF6 in the electric field was studied by M / s. HG Cooper and PS PQLLOCK in 4936 known for more than two decades, perfection on the commercial exploitation is achieved in 1960. These developments made it possible for low-pressure SF6 gas to be used in isolation switches and BIN are "for cooling purposes, some of the excellent properties SF6 gas that make its use ideal in the MAT circuit. switches are:

1. Inertia

2. No toxicity

3. Negative Electro nature

4. High dielectric strength

5. Cooling are the sole property

6. Chemical and thermal stability

7. Good thermal conductivity

8. Non-corrosive

9. No Flammable

The combined electric physical chemistry, and thermal properties of SF6 offer the following outstanding features when used in the power switch on the circuit.

1. Security

2. Size Reduction

3. Weight reduction

4. Simplified design

5. High level of reliability

6. Capacitive switching currents without restart

7. Very tow noise

8. Easy to manage

9. Easy Installation

10. Maintenance free service

2. Properties of sulfur hexafluoride (SF6)

a) Physical characteristics:

SF6 is a colorless, odorless, nonflammable. The fluorine atoms are placed in the corners of a regular octa hedra with the sulfur atom centrally placed at a distance of 1.58 angstrom units. The bonds are predominantly covalent and the equation of dissociation is

SF6 – à SF5 + F __________

The potential breakdown is 15.7 eV. SF6 gas is a very heavy gas and its density is about 5.5 times that of air. It is very stable. Is more compressible than air and follows the perfect gas law.

b) Electrical properties:

Di-electric strength of SF6 gas is 3 times that of air at atmospheric pressure and is only slightly reduced by the presence of air as an impurity. The increase in dielectric strength with increasing pressure. At a pressure of three bars, the dielectric strength becomes equal to the transformer oil. The molecule size and electro negativity explain this strength. The molecule provides a large diameter shock Electron. This results in the capture of electrons will be unable to create enough energy to others. Charged particles present. SF6moiecuie also has the ability to store energy in the electronic and vibration levels "of the molecule by forming stable ions of low mobility.

The dielectric strength of SF6 is unchanged over a wide range of frequencies. since SF6 has no dipole moment, dielectric constant does not vary with frequency. AT 27.30cy atmospheric pressure is 1.00191 dielectric constant and loss angle is 2 x 10-7.

The dielectric properties of SF6 will not change, even at low temperatures. Unlike the solid insulating material an electrical fault in SF 6 gas does not lead to a permanent deterioration of their properties. You lose control on all computers full can lead to a massive increase in pressure due to gas formation, but those risks do not exist in the case of SF6 filled equipment.

c) Arc cooling properties:

The cooling capacity is unique arc SF 6. The result is the high dielectric strength gas and very rapid recovery of dielectric strength after arcing occurs. SF6 is about 100 times more effective in this regard that the air in similar conditions. The low constant arc of time and its ability to absorb free electrons due to the electro negative nature makes it an excellent way for the interruption the arc. The movement of SF6 molecular complex allows it to absorb electrical energy and a stable negative ions. His tendency to the formation of negative ions around zero Current results in the rapid disappearance of the electrons released during arcing. Unlike oil, forming an arc in SF6 produces no deposits carbon or carbon tracking.

Electro-negative property of SF6 may be due to several factors, including major collision diameter. If electrons lost electric field can be absorbed before they reach sufficient energy to create additional current carrying particles when the collision, the distribution is may slow or even stop. The collision diameter of the SF6 molecule of great help in the capture of these electrons. energy can be stored in the vibration levels SF6 atom, forming stable negative ions of low mobility. Thus, the gas is electronegative in nature and shows. Large electron binding capacity. By So splendid sample of SF6 gas arc extinction performance.

The arc time constant is directly proportional to the radius of the arc makes possible to have large numbers of breaks at full capacity of the switch. The characteristic curve of the arch is such that b Termination of authority under. In a typical case where power extinction was the order of 20 KW for SF6 switch, the value of airflow switch was in the hundreds of kilowatts.

Some process of formation of SF6 ions are:

Resonance capture: SF6 + e-à (SF6) – SF5-+ F

formation of positive ions: SF6 + e-à (SF6) + 2e-SF5-+ H + 2e-

Excitation and dissociation: SF6 + e-à (SF6) + e-SF5-+ H + e

positive and negative ion Training: SF + e-à (SF6) + e-SF5 + F – + e

d) Heat transfer characteristics:

SF6 has excellent heat transfer characteristics, an important criterion for dielectric gas in power applications. The higher molecular weight, with low viscosity SF6 gas allows heat transfer by convention more effectively than common gases. The heat transfer coefficient of SF6 is approximately 2.5 TIP1 that air under the same conditions. Hence, when the switch is activated, the small temperature rise.

e) Wide temperature range:

SF6 in gaseous follows the ideal gas laws very closely. Consequently, the pressure change is only modest for a considerable change in temperature. The low points of sublimation SF6 dielectric ensures more even at low temperature the liquefaction temperature is-270C at a pressure of 12 Kg / cm ². Hence no heater is needed.

f) Toxity:

SF6 gas is nontoxic and produces no toxic effect on the human body. But the decomposition products produced by the discharge (SF4, SF2, S2, F2, etc.) are harmful. These products are minimized by controlling moisture in the switch and by absorbing the breakdown products of synthetic zeolite.

g) stability Chemical and Thermal

SF6 gas is inert and is one of the least reactive substances known in normal operating conditions. Can be heated in the quartz at 5000C, not least in the decomposition. SF6 will not react with water, acids and alkalis. Tests have shown the practice no corrosion of various metals exposed to SF6

Several constants) h:

Some of the exceptional properties of SF6 which makes it ideal for high voltage applications are:

Molecular weight .. 146.05

Sublimation point at 1 atm .. 63.9 ° C.

Gas density to 21.19 C at 1 atm .. 6.139

Liquid viscosity 13.52 ° C .. 0.305

Gas to 31.16 ° C .. 0.0157

critical temperature, etc. .. 318.80

critical pressure bars .. 37.772

cu.metre critical volume / g .. 1.356

Dielectric N2 rei at least 50 Hs = 2.3 -2.5 -1.2 .. MHS

dielectric constant at 25 ° C 1atm .. 1.002049 "

Conductivity Heat to 30 ° C, Cal / Sec-In ° C .. 3.36 x 10-5

3. Breakdown phenomenon in SF6:

Breakdown gas is produced when free electrons gain sufficient kinetic energy under the influence of an electric field and collide with neutral gas molecules release electrons of its exterior shell. A chain reaction as this results in an avalanche of electrons. In the case of greenhouse gases such as SF6 electro-negative this mechanism has been slightly modified. The free electrons are associated with the molecules forming negative ions. SF6 SF6 Z + ee. The negative ions are too massive to produce ionization by collision. This attachment is an effective way to remove the electrons that would otherwise have contributed to an avalanche of electrons. This particular behavior leads to rigidity high dielectric for electronegative gases.

The breakdown voltage of an electro-negative gas in a uniform field is a simple function of the product pressure and spacing. breakdown of the characteristics in nonuniform fields will be different because the main objective ionization may locally by the presence regions of high stress. This is the corona. This may be due to surface roughness, sharp corners, floating conducting or semiconducting particles. On computers SF6 special care is taken to ensure that these points do not exist in the switch to a fairly uniform field distribution can be achieved.

4. SF6 interruption Principles:

Techniques used for SF6 interruption can be classified into two:

a) Dual pressure.

b) The single pressure system.

The latter can be classified as dual flow nozzle fixed and a single piston flow switch series.

a) dual pressure system:

Isolation functions and disruption are held in separate chambers. SF6 at a pressure of 14 kg / m². cm. is stored in a high-pressure chamber. This is used to cool the SF6 are low pressure (2.5 to 3.5 kg / m². cm.) provides insulation. When the contacts separate under fault, high pressure gas is forced into the region arcing and then continue to the low pressure region. The gas thus exhausted in the region of low pressure is compressed again and returned to deposits under pressure. Arcing occurs between the tip of the bow and relieving arch ring contact area of the arc voltages. A filter with real student remains at the inlet of the compressor for all products of decomposition of gas can be absorbed before recirculation to the system. A controlled heating system thermostat is provided on the high pressure tank to prevent condensation of gas at low temperature.

b) system individual pressure:

In this case SF6 low pressure (3 to 6.5 kg / sq.cm.) provides insulation and energy for the interruption. The camera switch consists of fixed and mobile contacts, and the disposition of the piston in the balloon type of stationary contact. As the contacts move apart by guilt, the piston moves forward rapidly. This compresses the SF 6 within the fixed contact, and sanctify the forces of the gases in the arc resulting in the temple. The force with which the gas could be explosion depends on the design of the arrangement of the piston and the power control mechanism.

Another improvement is the type where magnetic switches globe greater force operating in the contact bar in motion, by force of magnetic repulsion. The short circuit current is passed through a set of fixed coils with the support of the Fed moving contact. A ring is placed and the secondary circuit magnetically coupled to primary coil. This ring also acts as a piston. This interaction. two fields produces a repulsive force and pushes the contact bar moving forward. The addition of simple magnetic transmission mechanism interruption improves the switch.

The single voltage system has a built-in advantage of simplicity in construction. No need additional compressor is needed in the double pressure. The manufacturing cost balloon-type equipment is lower.

5. Construction:

The arc suppression system uses a single synchronized flow pressure double balloon type design. This leads to a simple construction.

The SF 6 circuit breaker includes mainly the following:

1. Breaker Poles it.

2. Base box tube and mechanism of

3. Control Unit

4. Air Compressor electro-hydraulic operating mechanism

1.Movable cylinder (cylinder Puffer) 2.Moving Contact

Contct 3.Fixed 4.Insulating Nozzle

Trapped in piston 5.Fixed 6.Gas before compression

7.Compressed gas between 1 and 5

8.The arc is extinguished by the action balloon

5.1.Breaker Polo

The main functions a circuit breaker pole are made the switch. The pole of switch unit is composed of switch and isolator support.

The unit consists of switch tube fixed contact, guide tube, moving the contact tip, balloon or explosion of the cylinder and piston. The fixed contact tube is connected to the upper terminal through of. Contact support.

The guide tube is attached to the lower terminal. The other end of fixed contact tube and guide tube in which they are subjected an arc during the interruption of the arc nozzles are provided with arc quenching. the nozzles are made of graphite material that maintains a minimum contact wear. The moving contact tube is composed of spring finger contacts arranged in the form load of a ring. The front end of the movable contact tube is fitted with a ring of resistance insulating and arc ring arcs high strength materials arc

The cylinder explosion, which is composed of arc high insulation resistance material and the moving contact tube are rigidly connected together and connected to the operating rod in the support insulator. The piston explosion, which consists of aluminum platform is attached to the bottom terminal. The fixed contact tube, guide tube, moving the contact tube, the cylinder and piston are explosion explosion "All housed in a porcelain insulator. When the switch is in the closed position current flows from the terminal up and down through support contact terminals, the tube fixed contact, moving contact tube and guide tube.

The support insulator in addition to supporting switch unit provide insulation between live parts and ground parts. It houses the operating rod (isolation), one end is connected to the switch unit and other end connected to the mechanism.

5.2. Tube Base box mechanism:

The tube of the base that supports the pole switch mechanism and the box acts as a local air tanks. The closed box mechanism of the electromagnetic valve, the closure of the coil, trip coil and the cylinder operation. Lowercase mechanism lever locks the entire system to transmit the force of the operation mechanism of the box for the pole switch.

5.3.Control Unit:

This accommodates the gas pressure switches, gas detector density, gas pressure gauge, air pressure gauge, air valve heaters, auxiliary relays, terminal blocks, etc. for the electrical and pneumatic control and control of the switch. The air control devices and systems are common SF6 gas for 3-pole switch.

5.4. Compress

Given that the operating power requirement is higher as is MOCBS air compressor or the operating mechanism uses electro-hydraulic.

6. The principle extinction of the arc:

When the switch is in the closed position of the moving assembly bridges contact contact tube fixed and the guide tube. When an opening operation is started, the explosion of the cylinder piston moves toward the stationary explosion so that the SF6 gas explosion in the cylinder is compressed to a pressure required to turn off the bow. The compressed gas during the previous process is released only when the contacts are separated by the overall movement serving as contacts valve slide. In the instant of contact separation, the arc strikes between the front nozzle mitigate arc contact tube and the ring fixed arc contact the trunk movement. The compressed gas cylinder explosion in breaking free radical as the contacts separate. As the contact Retrofitting mobile, the arc between the front edge of the contact tip and ring fixed arcing movable contact ring is transferred from the arc the moving contacts of the nozzle guide tube, using a jet of gas and their own forces of electrodynamics. the arc is extended by the axial gas flow injectors and security lapse. While the arc is interrupted, the ignition cylinder, which makes arc resistant material enclosed isolation cooling the whole bow there to protect the porcelain insulator arcing effects. After arc extinction, the movable contact assembly and the shock wave is free of any part of the chamber can have a transition effect or influence the provider of electric field.

7. Operation principles:

7.1. Opening Action:

When the trip coil is activated, the valve area pilot is filled with compressed air filler valve and moves to right. The space in the operating cylinder is filled with compressed air from the air received and the piston is driven quickly to the left. operating rod in relation to the operating piston is pulled in the direction of opening to the balloon cylinder unit to high speed through the insulated operating rod insulator support. SF6 gas in the cylinder and the balloon is compressed SF6 gas explosion extinguished the arc is generated between the movement and fixed contacts.

Simultaneously with the opening movement, the cam rotates and causes the solenoid valve to return to its original position. As a result, compressed air in the space of the pilot valve is exhausted into the atmosphere and the charge valve is reset to the original piston. While the state remains open for link mechanism attached to the end of the piston.

7.2. Closing:

When the closing coil activated, the nature of the arc is rotated by the hook to be disconnected. So the line of the sector to free the roller rotates and the piston is driven in the closing address by the closing spring force at the end of closing, the binding mechanism is maintained in a state that is ready for subsequent opening operation.

8. Caution:

When operating the switch notes:

I) Maintain pressure SF6 gas and correct air pressure as specified.

2) Run the valves correctly.

3) Does allow ingress of moisture and dust in SF6 gas point.

4) Do not pump gas pipes and air pipes with any object.

5) Does not damage the seal and ring in the joint leak tight gas and air.

6) When you open the circuit interrupter handle manual. '

a) confirm that the main circuit is not active.

b) Be sure to turn off the power supply control.

c) Check that compressed air is released in the receivers.

d) Confirm that the operating rod and removed manual before operating the receiver to change air compressed.

7) Do not operate any other party to the instruction manual before filling SF6 gas driving to the rated pressure. Do not fill the compressed air before SF6 gas filling.

When control of the interior parts of the switch, air flows in the system long enough and confirm that the supply sufficient air is available before starting work.

9.Gas Leak Detection:

If leaks gas through any point, this can result in reducing the pressure and the consequent loss of insulation properties of gas leak detection is done with the help of a halogen type flame detector. The detector operates on the principle SF6 absorbs a certain number of electrons passing through an environment where the flow of electrons free. The free electrons are generated in the sector with a small radio active source in the presence of a carrier gas. these electrons are collected at the anode of the detector and the line small base current is amplified. When the detector probe is held near the joints of SF6 filled equipment and SF6 leaks if there will be variations in valve power amplifier due to absorption of electrons by SF6. The variation can be directly calibrated to indicate the magnitude of the leak.

9.2. Halting the presence of conducting particles:

This is done by performing a dielectric test when the test voltage is applied there will be a domestic crown in the case of metallic particles or sharp corners are present. The presence of internal discharges found with the help of an ultrasonic detector that is sensitive in the detection of noise due to the inner ring. The field of ultrasonic vibration frequency means Audible and indicates directly the sound intensity in decibels. The probe is pressed firmly against the tube box grounded while the driver is powered from current alternating voltage varies. If the noise disappears at low voltage, appears on some means of voltage and current is increasing, the fact is that the noise is due to the inner ring. It has also been observed that in some cases branched small fort to the bathroom in the areas of tension and dielectric particles burn led to low stress areas. The effect of the implementation of the particles in the breakdown strength of SF6 is more serious for power frequency voltage test for the voltage pulse.

10. The performance of SF6 circuit breaker:

SF6 gas circuit breaker combines features least profitable oil and blowing air switches and displays a number of additional advantages over both.

1) It is possible to have extensive operations break break near full capacity without undue wear.

2) Due to the rapid recovery of the dielectric through separation of contacts during the interruption.

a) These switches are Restrict free while changing the capacitive currents.

b) These switches are incentives to faults quickly and are capable of breaking every RRRV and high values

c) These switches are suitable for closing several short again with any reduction in breaking capacity

3) No need to change any parts in the breaking chamber, even after a period of ten years of service in the real system. This means there is virtually no maintenance problem for SF6 circuit breakers.

4) The operation is silent because the gas is used in a closed circuit. There will be no dumping of products in the atmosphere arc.

5) balloon-type switches are autonomous and independent as no auxiliary equipment is required.

6) Fire hazards are eliminated.

RELAY

A relay is an electrical switch that opens and closes under the control of another electrical circuit. In the original form, the switch is actuated by an electromagnet to open or close one or more sets of contacts.

Operation

When a current flows through the coil, the resulting magnetic field attracts an armature that is mechanically linked to a moving contact. The move makes or breaks the connection with a fixed contact. When the current to the coil is off, the armature is returned by a force of about half as strong as magnetic force of its relaxed position. Usually, this is a spring, but gravity is also commonly used in industrial motor starters. Most relays are designed to operate quickly. In a low-voltage application, this is to reduce noise. In a high voltage or high current application, this is to reduce arc.

If the coil is energized with DC, a diode is frequently installed in the coil, to dissipate the energy of the magnetic field in the collapse of deactivation, which would otherwise generate a voltage spike and cause damage to circuit components. Some automotive relays already include diodes in the relay box. Furthermore, a contact protection network, consisting of a capacitor and a resistor in series, can absorb the increase. If the coil is designed to be powered with air conditioning, a small copper ring bend, you can at the end of the solenoid. This ring "shadow" creates a small out of phase current, which increases the minimum tensile of armor during the AC cycle.

By analogy with the original device functions Electromagnetic, a solid state relay is made with a thyristor or solid-state switching device. To achieve electrical isolation can be used optical coupler is a light – light emitting diode (LED), along with a photo transistor.

Relay Types

• Interlocking relay
• Reed relay
• Relay Mercury Wetted
• Polarized relay
• Machine tool relay

• Contactor relay
• Solid state relay contactor
• Buchholz relay
• contacts forced-guided relay
• Solid State Relay
• Overload protection relay
• Pole & Throw

The following types of links are often:

SPST – Launch a single pole. These have two terminals that can connect or disconnect. Including two for the coil, such a relay has four terminals in total. It is ambiguous whether the pole is normally open or normally closed. The terminology "SPNO" and "SPNC" is sometimes used to resolve the ambiguity.

SPDT – Single Pole Double Throw. A common terminal connects to any of the other two. Including two for the coil, such as a relay has five terminals in total.

DPST – Double Pole Single Throw. These have two pairs of terminals. Equivalent to two SPST switches or relays actuated by a single coil. Including two for the coil, for example a relay has six terminals in total. It is ambiguous whether the pole is normally open, normally closed, or one of each.

DPDT - Polo Double Shot. These have two rows of pins to change the format. Equivalent to two SPDT switches or relays actuated by a single coil. This relay has eight terminals, including in the coil.

QPDT - Quadruple Pole Double Throw. Often referred to as Quad Pole Double Throw, or 4PDT. These have four rows of change terminal format. Equivalent to four SPDT switches or relays actuated by a single coil, or two DPDT relays. In total, fourteen terminals including the coil.

• protection relay
• Real Overcurrent
• Distance Relay

Lightning and Surge INSULATION COORDINATION

I. Introduction:

Electrical systems in nature involving two forms of protection as current and voltage in over current protection of electrical equipment are well known to all, not elaborated here. Over voltage protection on the other hand, remains a relatively new to many engineers. Both types protection also necessary to operate the security system.

The importance of surge protection for power system not be overemphasized. Major equipment failures, costly repairs, personal safety and plant downtime are some consequences of inadequate protection surge voltage.

The surge arresters are designed to limit dangerous surges in the system. If the lighting or the production system-a safe values when they occur in power systems. A lightning is a voltage limiter device. Functions are available for download energy associated with the state system voltage limit and the interruption of current scholarship that follows the transient current through the arrester and the return to a state of isolation for the prepared tension over next occurrence.

In carrying out its voltage limiting function, certain features of protection arresters must be coordinated with the insulation levels prevailing in the system being protected. Isolation is a basic factor to be considered in implementing lightning rod in a system. Insulation coordination is only a small part of the over all subjects of arrester application. Several other factors must also be considered by the engineer when selecting surge protection. The location of the rod, the interconnection of the ground wires, the level of isolation of the protected equipment and the rating of the surge arresters are important in protecting the equipment from the harmful effects of voltage.

Lightning II.Surge operation:

The basic operation of a surge arrester is unique. As it noffi1al, a lightning rod should act as an insulator. When a high voltage surge occurs. The arrester must cease to be an insulator and has to turn in a short to ground in millions Thus, in one second. The operation of the most widely used type of lightning courage, the kind of lightning rod issue. Other types of lightning, like the expulsion arrester and the line of oxide of arresters (gapless arresters) are in decline or too new for general discussion at this time. The active elements of a type of valve arresters are the sparks and the valve block. they are in a porcelain tank for the protection of the atmosphere and outer insulation.

All vacuum consists of a series of air spaces in the series with sufficient dielectric strength to withstand the higher frequency of system power. For more severe conditions voltage, the gap must always, a breakdown voltage level below what some insulation withstand voltage level of the equipment being protected, other wise and damage equipment downtime or plant output. the differences thus serves as the switch that turns on the rod. the voltage level at which the arrester is the passive (insulation) to the active (conducting) state, is called the spark over voltage.

The valve block controls what happens after the lightning has ignited. If a gap is only used once a surge has been diverted to ground, a dead short between line and ground and 50 hertz power system tries to flow to ground causing a fuse, become more narrow or a switch to operate the interruption of the current system failure.

The valve element does exactly as its name suggests. Performed when the current is flowing and will stop increasing when the 50 Hz line begins to flow. the valve block is able to do this because it is made of a material's nonlinear resistance of silicon carbide. The valve block offers very high resistance at 50 Hz time that shows a low resistance to surge. In addition, it also consumes energy surge through it.

Spark and more discharge voltage are two characteristics of a lightning protection that are used to calculate margins of protection when testing coordination isolation. These protection features are published by manufacturers of lightning.

III. Arrester Rating:

There are three classifications of arresters used for protection of voltage across a system.

1.Distribution Type:

The arresters are generally used in distribution systems security equipment. Standards distribution arresters are used to protect oil. insulated distribution transformers, these lightning arresters are also used as input line, 11kV and 22kV lines. They are the lowest cost.

2.Intermediate Type:

These units cost about two or three times more than the distribution units equivalent. To this end, the rod provides maximum spark over and voltage discharge characteristics that give a greater margin of protection capacity compliance with high power levels. These arresters also have a pressure relief system for the safe evacuation of internal pressure if the unit falls before porcelain shell has the possibility of rupture. These are used for lightning protection of power transformers in ie110/33/22/11KV LV sub-transmission and substation 66/22/11KV substation.

3.Station Type:

These arresters offer the best protection features and the highest thermal capacity but cost double the equivalent of intermediate units. Like lightning intermediate arresters have a station decompression system to safely evacuate the internal pressure if the unit fails before a deposit china has the possibility of rupture. These arresters are generally used at 230 kV, 110 kV and 66 kV systems.

4.Basic Insulation level:

            Basic Impulse Insulation Level (BIL) is the level of voltage equipment insulation can withstand without damage. The insulation withstand voltage is a function of time. Inorder to establish tension-time levels of pulse transformer insulation standard test impulse withstand voltage tests are standard in selected units as a type test. The pulse transformers are subjected to stress tests (a nominal BIL) and a chopped wave test (15% above BIL). A steep front – Testing wave (65% above BIL) also performed on some units. A curve drawn through these three points defines the minimum insulation withstand curve for isolation coordination (Fig. 3) support a certain level for the transformer is above the curve traced.

5. Surge arrester application:

With an understanding of how a lightning rod performs its functions and knowledge of equipment insulation, we can now move to the area of application and consider the various factors that make up the application surge regard to the protection of voltage across the transformer, the selection of protective Surge merit are considered carefully. Several factors must be taken into account in arriving at a reliable and at the same time, the business of protection. The points are:

i) Selection of the rated voltage.

ii) The selection according to the rules, codes, recommendations for insulation coordination.

i) Evaluation arrester:

The rated voltage of an arrester is defined as the highest voltage of 50 Hz at which the arrester is designed to operate, and close its function after a wave has passed. Due to system implementation grounding and connection, this, stress is often higher than the voltage phase to ground / in the healthy phases will increase temporarily and dependent upon the making land or the system. The selection of a rated voltage of the arrester station depends on the connection of the grounding and voltage rating of the system.

Also, the voltage across an arrester during a discharge is directly proportional to the rated voltage arrester that is, an increase of 10,000 amp produces a discharge voltage higher if it is flowing through a 10KV downloader of what makes flowed through a lightning rod 9KV is generally desirable in terms of protective equipment to select the lowest voltage rating for the application.

ii) the lightning location:

Surge arresters should always be located as close as possible to the terminals of the protected equipment. For transformer protection, arrester mounting the transformer directly into the best insurance. An appreciable distance between the surge arrester, and the protected equipment reduces the protection offered by lightning and also increases the voltage applied to the processor when the discharge voltage. Also due to the additional travel distance between equipment and lightning, waves could increase beyond the point of damage to the equipment before the lightning came to her rescue.

n addition, the lightning rod connection cables should be as short as possible, because of its contribution to the voltage discharge of tension. During the current flow to ground through of a lightning rod, the interconnecting cables to make a contribution of stress due to the current passing through an impedance. Depending on the magnitude of the wave, the rate of increase of the driver, a typical value of the contribution of voltage to the discharge voltage by interconnecting cables ie 1.6 KV / foot.

In practice, the protection of range is given by the simple formula.

L = U – Ua When x V

2 XS

L = range of lightning protection in meters

(Measured along the line)

Withstand Voltage U = of the protected equipment in KV. (BIL of equipment)

Ua = voltage spark a lightning rod in kV (peak) system. Under earth fault, voltage

V = rate of progression of the wave with

Line V = 300 m / sec micro.

V = cable 150 meters / sec micro.

S = Slope of the input wavefront in the KV / sec.

(Protection a range of lightning increases with the difference between the impulse voltage IV and Va voltage spark Therefore, a downloader with the level of protection tends to expand the range of protection)

iii) Interconnection field:

It is essential that the arrester ground terminal will be interconnected with the tank and secondary transformer neutral to provide reliable surge protection for transformers.

Iv) Coordination Insulation.

Now we consider the selection of a lightning conductor according to the rules, codes or recommendations for coordination isolates. The calculation of the margin of protection is the main part of a file. insulation coordination of the study. Insulation coordination is the process of comparing the driving force of isolation stress that there may be a lightning rod for the severity of the voltage discharge for which protection is sought. For a transformer, this means a comparison of the insulation volt-time withstand the momentum curve and change back and spark another wave voltage discharge curve of the arrester.

After determining the rated voltage of a lightning rod, the level of protection must be carefully selected. For complete protection of equipment, the level "Protection" to know. the level at which the tensions are omitted by the rod, should be less than the level of support by a factor of at least 1.2 for 15 for lighting surges and switching surges. The value thus selected should be compared with that given in the ISS or the technical details provided by the arrester manufacturing.

To reach the discharge voltage of a lightning rod for these calculations voltage discharge of 10,000 amperes. increase is normally used. The following formulas define these two margins of protection calculations:

CWW-IX of FOW SO + BIL-DV)

MP1 = de CWW MP2 x 100% = 100% x BIL

Where

In greeted CWW = Picado-voltage withstand transformer winding BIL = 1.15

SO = FOW Wavefront more spark KV surge (CREST)

BIL = Basic impulse insulation level of the transformer.

DV = discharge voltage arresters at 10 KA rise.

IX = voltage contribution of the connecting cables at a rate of 1.6 KV / ft

MP = Margin of Protection

Insulation coordination, an important aspect to consider when protection surge is to be given to processors with reduced BILS

Direct vi Shock Protection:

i) Protection against direct hits can be handled by the shield of the team for the delivery station of any

a) mast or wires or

b) a networking cable above ground so that the equipment and switches are all in the protected area.

ii) The protected area to the bar of a mast is generally assumed as a cone with base radius equal to the height of the rod or a pole on the ground.

iii) For small substations can be sufficient to run one cable from GI front of the station from the towers of the adjacent line. Extra cables can be run from the tower to the structure and on the station.

iv) The grounds of the station shield must be securely fastened to the ground station bus prevent potential difference between the increase in armor and other parts of the station g full.

SECURITY IN SUB-STATION

Prevention of damage to the equipment's and men working in the then due to accidents is an essential aspect in any establishment. Accident prevention, an unforeseen event which is a more essential aspect of any business or organization.

As accidents occur mainly due to the implementation unsafe actions and circumstances, these accidents can be prevented by taking safety measures, implementation of safety procedures and safety rules.

General security methods:

I. Although the implementation of any work, that some of the equipment or the line must be isolated from the supply.

2. Using bars unloading, loading, the power if it is to be discharged.

3. Using Earth bars, all stages / conductive path is taken from land owned by ensuring good earthing.

4. When even the opening of a switch AB or removal of fuses, it is also advisable and preferable to use rubber gloves.

5. The rope belt use is another method of security be taken to work in high places.

Security methods adopted in substations:

In any work to be attended to any line, first and foremost, the topic of work is to obtain the permission of the competent authority responsible for auditing the execution of the work, including the date, time, duration, work, parties, etc affected.

For feeders grid and Seasons the official responsible for issuing permits is SE (LD Centre), Madras, for 110 KV, 66 KV, radial lines Superintending Engineer / Distribution is the approving authority. Likewise the InCharge 33 KV Distribution Engineering Division is the approving authority.

Above information with the list of authorized officers attached (Appendix I)

Without obtaining the permission of the competent authority not be issued LC nor endorsed by anybody. If the above procedure is not followed, no more than a suicide. In addition also means the killing of others.

So, after to receive proper approval of heading clear is to be issued the requested party. But the subject and the recipient should be aware of / have full knowledge about SS team details, the room control panel etc.

The clear line person issuing clearly must include the following:

a) What triggered the switch

b) What changes opened AB

c) If the ground is made

d) What is the safest place / Line to carry out the accomplishment of work

Safety devices Control Room:

1) Key Board should be able to open so that the keys can be quickly removed for any emergency.

Keyboard clear line must be closed until able to prevent others using the keys inside, before the cancellation of line clear permit.

The keys should be placed on the key board in an orderly manner according to their number. Otherwise, the requested lock could not be opened in time and the possibility of opening a wrong lock can happen.

2) Rubber mat should be provided on the ground in front of the board.

3) The following information must be clearly visible in the control room.

Approved operating instructions for all equipment.

Breaking down the instructions.

Instructions even for emergency operations to be carried out if Buchholz relay operation. differential relay, Travel in the control group, total power failure, network failure. The operator must be fully familiar with the instructions above and must be able act swiftly and effectively.

4) The DC Board that contains the provision of cable. A cable design panel wiring diagram and design grounding should be displayed in the control room. This is necessary to attend the faults immediately after its occurrence.

5) DC earth leakage system should be available.

6) There should be no faulty power outlets, switches and sockets in wiring the control room.

7) A respirator should be available in ready condition.

stools made of insulation material should be used for the operation of high voltage equipment of communication (telephones).

9) appropriate number of rubber gloves, rope belt discharge bars and rods of land in good condition should be available in the control room.

Battery room

1. Battery room must be enclosed in the condition.

"Naked flame is prohibited within the battery room" and " Smoking prohibited "written warnings must be kept in front of the battery compartment.

2. An exhaust fan should be running.

3. Accurate test cell volt DC meters, water meters and thermometers must be available in the battery room.

4. pilot cell voltage, specific gravity and temperature should be taken every week.

5. The specific gravity should not be kept below in 1195 to 15.6 º C and below 1183 at 32 years. 20 ° C. The battery should never be allowed to discharge below 1160.

6. Cell voltage should be between 1.95 V to 2.05 V. The battery should not be allowed to discharge less than 1.85 V.

7. Batteries should be allowed or not to charge more than undercharge. There should also be kept idle.

8. electrolyte level should be checked every shift. You must ensure that the level is 10 mm above the top of the plates.

9. weak cells should be rectified at the time.

10. While taking specific gravity readings, be careful not to allow the acid in contact with eyes.

Security arrangements for processors:

1. Transformers will be maintained regularly as per schedule. High-voltage switches on either side of low voltage should be isolated after reduction of the load, activating the breakers.

2. Kiosks and OCB: All live parts of the cockpit tape should have HT. Wiremesh To be protected. It should be rodent-proof. The keys are to be kept with latch. When once to open the door of the kiosk, kiosk stumbled link should be opened by the lock key. The opening of links must be physically verified. After taking all precautions before, the tank must be reduced down. Proper care is to be taken and must be taken into account that the offer is available on the roof.

oil leaks must be stopped. Back feeding is avoided.

Cotton waste should not be used for cleaning.

3. AB switches:

Manage the switch B is to be properly grounded. The leaves should be kept in the open position. It should not be automatically closed, proper maintenance must be done for it. AB reed switch will be opened fully. AB switches will remain fixed in both conditions. AB switches will open only after tripping the breakers.

. Lightning rod 4:

arresters are used to circumvent the beam suddenly and therefore to protect the computer. Only after the correct download performed on the rod, you should try to meet maintenance.Fencing be provided around lightning. Door lock agreements is to be provided. Separate connections of land are provided for lightning.

5. Current transformers:

Current transformer secondary is a circuit during maintenance and testing. Before any test, the current transformers must be discharged.

6. potential transformers:

potential transformer primary side is to be grounded for maintenance and testing. The secondary side is to be connected grounded in one place. Each time a connection to or remove meters in the secondary side of die potential transformer fuses should be removed and renewed.

7. HT capacitors and coupling capacitors:

Capacitors should be provided within the fencing. Before attempting any work good performance should be done. Should be attempted only for maintenance. Proper grounding must be provided during the works. After completion of the work, ground shall be removed.

8. Earth pits:

Sub-station ground connections must be properly maintained so that the ground resistance is minimal. The water should be poured on the earth boxes daily. Earth connections must be able to protect people working in electrical equipment and protection equipment during a fault strong current. Earth resistance should not exceed the following limits.

Grid stations: I Ohm Other substations .. 2 Ohm.

Distribution transformers .. 5 ohms.

Should be a clearance of 5 feet between the fence the substation and electrical equipment points. The fence must be grounded in every 200 meters separately. In general, the ground should not be linked closely Grounding a sub-station. But when the height is less than 5 feet of ground near the feet should be linked to the grounding of the substation. Doors iron fence in sub-station also should be grounded separately.

9. Fire fighting equipment:

These teams are to take to good condition and working. adequate maintenance schedule should be done to keep them in good condition. These teams should be kept at an easily access to emergency use immediately below. lots of dry sand, apply whenever necessary. empty buckets have to be provided.

10. SS Yard:

1. SS must have patio fencing.

2. Unauthorized persons should not enter the courtyard

3. Cable ducks will be provided with slabs.

4. Better lighting is to be provided for the yard.

5. A board with a screen warning that "Umbrella" palo Dogs should not be brought inside the yard is to be given to the entry courtyard.

6. A separate room is to provide for the maintenance of empty drums. At the entrance to the room "No Smoking" board is to be provided.

General

1. The territory of the operating point that was declared security work is to be clearly identified by tying a rope. Within this limit will be defined hanging green flag. Outside of this boundary is not safe to work is to be identified by a red flag.

NOTE 2. Whenever necessary together as "Men at Work" "Do not turn on" Safe for work ", etc, must be provided.

3. If any unauthorized unqualified staff moving to be near the equipment, he can do it with the help and under the watch of an expert staff and authorized.

4. The conversation is strictly prohibited the execution of any work of cunning. It should be totally avoided especially when the work is carried out at any bars.

5. Placement materials, tools and plants and men have to be at a safe distance from the Live. parties.

6. T & P, such as keys, etc must be lifted and brought down only by ropes and not throw and catch.

7. Study and safe ladder with steps at appropriate intervals to use. To avoid slipping of the ladder, the necessary precautions to be taken in the bottom of the scale, providing Gunni empty.

8. Elevation any ladder or bars (the Earth) will take place only horizontally. Vertical

lifting can cause damage by disruption with the safety distances.

9 The art bus line links', which remains open to do a job on the OCB and

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