Report Siap Explain Switchgear and Switchgear Maintenance

7/30/2019 Report Siap Explain Switchgear and Switchgear Maintenance

1/25

1. EXPLAIN SWITCHGEAR AND SWITCHGEAR MAINTENANCE

In an electric power system,switchgear is the combination of electrical disconnect

switches, fuses or circuit breakers used to control, protect and isolate electrical equipment.

Switchgear is used both to de-energize equipment to allow work to be done and to

clear faults downstream. This type of equipment is important because it is directly linked tothe reliability of the electricity supply.

One of the basic functions of switchgear is protection, which is interruption of short-circuit

and overload fault currents while maintaining service to unaffected circuits. Switchgear also

provides isolation of circuits from power supplies. Switchgear is also used to enhance system

availability by allowing more than one source to feed a load.

HIGH VOLTAGE SWITCHGEAR

A section of a large switchgear panel, in this case, used to control on-board casino boat power generation.

TRAM SWITCHGEAR
http://en.wikipedia.org/wiki/Electric_power_systemhttp://en.wikipedia.org/wiki/Fuse_(electrical)http://en.wikipedia.org/wiki/Circuit_breakerhttp://en.wikipedia.org/wiki/Fault_(power_engineering)http://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Fault_(power_engineering)http://en.wikipedia.org/wiki/Circuit_breakerhttp://en.wikipedia.org/wiki/Fuse_(electrical)http://en.wikipedia.org/wiki/Electric_power_system


2/25

You can prevent switchgear failure with proper maintenance.When switchgear malfunctions, the consequences are often catastrophic. Damage to the

switchgear itself can be extremely expensive, but that pales in comparison to corollarydamage and the potential hazards to people. Thus, implementing an effective switchgeartesting, inspection, and maintenance program is essential. Even switchgear labeledmaintenance free requires periodic testing and maintenance.Develop a maintenance program. The many approaches to switchgear maintenancerange from continuous online monitoring to do nothing (also called run-to-failure).Predictive and preventive maintenance programsincluding most of the National FireProtection Association (NFPA) and InterNational Electrical Testing Association (NETA)recommendationsfall in the middle of this range. Most real-world maintenance programsare a combination of these approaches. For instance, replacing indication lights only whentheyve failed is an example of run-to-failure maintenance. On the other hand, maintainingdisconnect switches on a periodic basiscleaning, lubricating, and exercising themis anexample of preventive maintenance. Annual visual and thermographic inspections on busconnections and breakers are examples of predictive maintenance.Developed by the airline industry and later adopted by other industries, reliability centeredmaintenance (RCM) is another approach. RCM is a systematic and comprehensive methodappropriate where equipment reliability is critical. It involves analyzing system criticality andcomponent failure modes, evaluating those failure modes and the appropriate maintenanceactivities for each component and then determining what is the most appropriate andeffective preventive maintenance activity for each component. RCM programs improveelectrical system reliability, and experts credit RCM programs with improving safety andmanagement of spare parts, decreasing repair costs, shortening outages, and reducingoverhaul frequency.

Manufacturer maintenance recommendations may or may not suggest maintenancefrequency. The 2001 NETA standard provides a maintenance frequency matrix that givesrecommendations based on the level of reliability required and the condition of theequipment.


3/25

The NFPA standard also includes suggested maintenance frequencies. They vary (typicallyfrom three months to six years) depending on system criticality and the environment in

which the equipment is located. Because no manufacturer or standards-making body canpresume to know how these conditions differ in your installation, its impossible for them tocome up with a meaningful maintenance frequency. On one hand, you want to minimize thenumber of maintenance outages; on the other, you dont want a switchgear failure to occur.Part of maintaining switchgear is ensuring your protective devices operate in the rightsequence. But how often must you verify that the settings and sizes are correct? Any timeyou have a change on the utility system or to your own system, you must confirm the shortcircuit withstand and interrupting ratings of your equipment are still adequate. A short-circuit study determines the magnitudes of available short-circuit current at each of yourswitchgear locations. A proper study will identify any switchgear that available short-circuitcurrent would overstress.Have your breakers tripped or fuses blown without a fault occurrence? Did the wrong deviceoperate when a fault occur? A coordination study provides device settings so breakers andfuses in your facility can coordinate and operate selectively. That is, a fault near the end ofyour circuit will cause the nearest upstream breaker or fuse to operatenot your mainbreaker. If you dont know whether your system coordination is correct, do a coordinationstudy long before the next maintenance outage.


4/25

Plan for the maintenance outage.

The following steps will help you formulate a comprehensive maintenance action plan and inturn an effective switchgear maintenance program. Prior to the outage:

Review your equipment history. What failures have occurred? Are you aware of any repair or

refurbishment needs? Review the drawings and other documentation. Are the relevant drawings current? Do you

have the correct instruction manuals? Perform visual inspections, thermal scanning, partial discharge testing, and other testing

before the outage so you can take corrective action when it happens. Identify and order all materials required for the outage. Take lead times into account. Develop a specific work plan and schedule. Communicate this information to all involved

personnel, and keep your end-users updated on the big picture. Conduct the tailgate safety meeting to be sure each person understands any dangers,

special circumstances, and related work assignments. During the outage: Shutdown the switchgear and apply protective grounds. Follow lockout/tagout procedure.

Barricade and put up warning signs as appropriate. Check and correct any drawing inconsistencies or connection questions. Perform inspections and cleanings. Disconnect as necessary for tests. Make any planned repairs, changes, or upgrades. Perform measurements and tests. Based on test results, make additional repairs. Concluding the outage: Re-connect and torque connections. Account for all tools and personnel. Make a visual check of all work. Remove grounds and then test to ensure you have no unintentional grounds. Energize switchgear and verify normal operation. Remove barricades and signs, and follow appropriate procedures to clear the lockout/tagout

condition. After the outage: Interview crews about problems they may have encountered. Ask them for

recommendations for improving response efforts during the next outage or preventingproblems that occurred in this one.

Prepare a report of maintenance outage and test results. Include trending and analysis ofresults and recommendations for future maintenance as appropriate.

Making maintenance happen.

Switchgear maintenance is usually considered a low priority by most management teams,who defer or ignore it until a failure occurs. At many facilities, the maintenance crews takeonly some of the easier steps. However, experience shows this is an economic dance withthe devil. When you fail to conduct the proper maintenance, the risk of loss is high. But asolid maintenance program is much less costly than the impact of switchgear failure, whichcan include injury or death, lost product and production, as well as clean-up and switchgearreplacement costs. When you give maintenance the thought and effort it deserves, youimprove safety, reliability, uptime, and profitability.


5/25

2. EXPLAIN TYPES OF SWITCHGEAR

A piece of switchgear may be a simple open-air isolator switch or it may be insulated by some other

substance. An effective although more costly form of switchgear is gas insulated switchgear(GIS),

where the conductors and contacts are insulated by pressurized sulfur hexafluoridegas(SF6). Other

common types are oil or vacuum insulated switchgear.

The combination of equipment within the switchgear enclosure allows them to interrupt fault currents

of thousands of amps. Acircuit breaker(within a switchgear enclosure) is the primary component that

interrupts fault currents. The quenching of the arc when the circuit breaker pulls apart the contacts

open (disconnects the circuit) requires careful design. Circuit breakers fall into these five types:

Oil

Oil circuit breakers rely upon vaporization of some of the oil to blast a jet of oil through the arc. The

vapor released by the arcing consists hydrogen gas. This gas is very effective at cooling the arc so

that dielectric properties are restored at current zero.
http://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Circuit_breakerhttp://en.wikipedia.org/wiki/Circuit_breakerhttp://en.wikipedia.org/wiki/Circuit_breakerhttp://en.wikipedia.org/wiki/Circuit_breakerhttp://en.wikipedia.org/wiki/Gas


6/25

Air

Air circuit breakers may use compressed air (puff) or the magnetic force of the arc itself to elongate

the arc. As the length of the sustainable arc is dependent on the available voltage, the elongated arc

will eventually exhaust itself. Alternatively, the contacts are rapidly swung into a small sealed

chamber, the escaping of the displaced air thus blowing out the arc.

Circuit breakers are usually able to terminate all current flow very quickly: typically between 30 ms

and 150 ms depending upon the age and construction of the device.

Gas

Sulfur hexafluoride circuit breaker

Gas (SF6) circuit breakers sometimes stretch the arc using a magnetic field, and then rely upon the

dielectric strength of the SF6 to quench the stretched arc.


7/25

Hybrid

A hybrid switchgear is one that combines the components of traditional air-insulated switchgear (AIS)

and SF6 gas-insulated switchgear (GIS) technologies. It is characterized by a compact and modular

design, which encompasses several different functions in one module.

Vacuum

Circuit breakers with vacuum interrupters have minimal arcing characteristics(as there is nothing to

ionize other than the contact material), so the arc quenches when it is stretched by a small amount

(


8/25

Carbon dioxide (CO2)

Breakers that use carbon dioxide as the insulating and arc extinguishing medium work on the same

principles as an SF6 breaker. By switching from SF6 to CO2 it is possible to reduce the CO2 emissions

by 10 tons during the product life cycle.


9/25

3. LOW VOLTAGE SWITCHGEAR

Low Voltage Switchgear refers to switchgear which is rated for a voltage of 600V and

below. Low voltage switchgear includes switches, fuse gear, enclosures, connection devices

and cable distribution cabinets.

The function of any switchgear is Electrical protection, electric isolation and local and remote

switching.

The switchgear typically consists of a section in the front consisting of the circuit breakers,

meters, protective relays. Behind the front section, is the bus section consisting of the

busbar and behind it is the cable entry section where the cables are routed.

Low voltage switchgear can be broadly classified into two types, outdoor types and indoor

types.

Outdoor type switchgear differs from indoor type switchgear due to the presence of a

weather-proofing enclosure. Bus bars are usually made of copper or aluminium.

Modern low voltage switchgear products consist of integrated modules consisting

of switchgear, metering and protective features. These integrated modules are driven

by microprocessors.

This article is the first in a series of articles focusing on Low Voltage Switchgear
http://2.bp.blogspot.com/_jbHyppMByw8/S_qYq-eqIvI/AAAAAAAAEM4/sWdejZVFuhc/s1600/lv+switchgear.jpghttp://2.bp.blogspot.com/_jbHyppMByw8/S_qYq-eqIvI/AAAAAAAAEM4/sWdejZVFuhc/s1600/lv+switchgear.jpg


10/25

4. EXPLAIN SINGLE PHASE DISTRIBUTION SYSTEM

A single-phase electric power supply is the distribution of alternating current electric power

where all the voltages of the supply vary in unison. Single-phase distribution is used when

loads are mostly lighting and heating, with few large electric motors. A single-phase power

supply has two hot legs or conductors, which have a sine wave that are 180 degrees apart.

In electrical engineering, single-phase electric power refers to the distribution

ofalternating current electric power using a system in which all the voltages of the supply

vary in unison. Single-phase distribution is used when loads are mostly lighting and heating,

with few large electric motors. A single-phase supply connected to an alternating

current electric motor does not produce a revolving magnetic field; single-phase motors

need additional circuits for starting, and such motors are uncommon above 10 or 20 kW in

rating.

In contrast, in a three-phase system, the currents in each conductor reach their peak

instantaneous values sequentially, not simultaneously; in each cycle of the power frequency,first one, then the second, then the third current reaches its maximum value. The

waveforms of the three supply conductors are offset from one another in time (delayed

in phase) by one-third of their period. When the three phases are connected to windings

around the interior of a motor stator, they produce a revolving magnetic field; such motors

are self-starting.

Standard frequencies of single-phase power systems are either 50 or 60 Hz. Special single-

phase traction power networks may operate at 16.67 Hz or other frequencies to power

electric railways.

In some countries such as the United States, single phase is commonly divided in half to

create split-phase electric power for household appliances and lighting.
http://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Phase_(waves)http://en.wikipedia.org/wiki/Utility_frequencyhttp://en.wikipedia.org/wiki/Hertzhttp://en.wikipedia.org/wiki/Traction_power_networkhttp://en.wikipedia.org/wiki/Split-phase_electric_powerhttp://en.wikipedia.org/wiki/Split-phase_electric_powerhttp://en.wikipedia.org/wiki/Traction_power_networkhttp://en.wikipedia.org/wiki/Hertzhttp://en.wikipedia.org/wiki/Utility_frequencyhttp://en.wikipedia.org/wiki/Phase_(waves)http://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Alternating_current


11/25

5. EXPLAIN THREE PHASE DISTRIBUTION SYSTEM

Three-phase electric power is a common method ofalternating-current electric

power generation, transmission, and distribution.[1]

It is a type ofpolyphase system and is the most

common method used by electrical grids worldwide to transfer power. It is also used to power

large motors and other heavy loads. Athree-phase system is usually more economical than an

equivalent single-phase or two-phasesystem at the same voltage because it uses less conductor

material to transmit electrical power.[2]

The three-phase system was independently invented

by Galileo Ferraris, Mikhail Dolivo-Dobrovolskyand Nikola Tesla in the late 1880sIn a three-phase system, three circuit conductors carry threealternating currents(of the same

frequency) which reach their instantaneous peak values at one third of a cycle from each other.

Taking one current as the reference, the other two currents are delayed in time by one third and two

thirds of one cycle of the electric current. This delay between phases has the effect of giving constant

power transfer over each cycle of the current and also makes it possible to produce a rotating

magnetic field in anelectric motor.

Three-phase systems may have aneutralwire. A neutral wire allows the three-phase system to use a

higher voltage while still supporting lower-voltagesingle-phaseloads. In high-voltage distribution

situations, it is common not to have a neutral wire as the loads can simply be connected betweenphases (phase-phase connection).

Three-phase has properties that make it very desirable in electric power systems:

The phase currents tend to cancel out one another, summing to zero in the case of a linear

balanced load. This makes it possible to reduce the size of the neutral conductor; all the phase

conductors carry the same current and so can be the same size, for a balanced load.

Power transfer into a linear balanced load is constant, which helps to reduce generator and motor

vibrations.

Three-phase systems can produce a magnetic field that rotates in a specified direction, which

simplifies the design of electric motors.
http://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Electric_power_generationhttp://en.wikipedia.org/wiki/Electric_power_transmissionhttp://en.wikipedia.org/wiki/Electric_power_distributionhttp://en.wikipedia.org/wiki/Three-phase_electric_power#cite_note-1http://en.wikipedia.org/wiki/Three-phase_electric_power#cite_note-1http://en.wikipedia.org/wiki/Three-phase_electric_power#cite_note-1http://en.wikipedia.org/wiki/Polyphase_systemhttp://en.wikipedia.org/wiki/Electrical_gridhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Single-phase_electric_powerhttp://en.wikipedia.org/wiki/Two-phase_electric_powerhttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Three-phase_electric_power#cite_note-2http://en.wikipedia.org/wiki/Three-phase_electric_power#cite_note-2http://en.wikipedia.org/wiki/Three-phase_electric_power#cite_note-2http://en.wikipedia.org/wiki/Galileo_Ferrarishttp://en.wikipedia.org/wiki/Mikhail_Dolivo-Dobrovolskyhttp://en.wikipedia.org/wiki/Nikola_Teslahttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Ground_and_neutralhttp://en.wikipedia.org/wiki/Ground_and_neutralhttp://en.wikipedia.org/wiki/Ground_and_neutralhttp://en.wikipedia.org/wiki/Single-phase_electric_powerhttp://en.wikipedia.org/wiki/Single-phase_electric_powerhttp://en.wikipedia.org/wiki/Single-phase_electric_powerhttp://en.wikipedia.org/wiki/Single-phase_electric_powerhttp://en.wikipedia.org/wiki/Ground_and_neutralhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Nikola_Teslahttp://en.wikipedia.org/wiki/Mikhail_Dolivo-Dobrovolskyhttp://en.wikipedia.org/wiki/Galileo_Ferrarishttp://en.wikipedia.org/wiki/Three-phase_electric_power#cite_note-2http://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Two-phase_electric_powerhttp://en.wikipedia.org/wiki/Single-phase_electric_powerhttp://en.wikipedia.org/wiki/Three-phasehttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Electrical_gridhttp://en.wikipedia.org/wiki/Polyphase_systemhttp://en.wikipedia.org/wiki/Three-phase_electric_power#cite_note-1http://en.wikipedia.org/wiki/Electric_power_distributionhttp://en.wikipedia.org/wiki/Electric_power_transmissionhttp://en.wikipedia.org/wiki/Electric_power_generationhttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Electric_powerhttp://en.wikipedia.org/wiki/Alternating_current


12/25

6. EXPLAIN PROTECTION AND CONTROL SYSTEM IN SWITCHGEAR

We all familiar with low voltage switches and re-wirable fuses in our home.The switch is used to manually open and close the electrical circuit in ourhome andelectrical fuseis used to protect our household electrical circuit fromover current and short circuit faults. In same way every electrical circuitincluding high voltageelectrical power systemneeds switching and protectivedevices. But in high voltage and extra high voltage system, these switchingand protective scheme becomes complicated one for high fault currentinterruption in safe and secure way. In addition to that from commercial pointof view everyelectrical power systemneeds measuring, control and regulatingarrangement. Collectively the whole system is called Switchgear andProtection of power system. The electrical switchgear have beendeveloping in various forms.

Switchgear protection plays a vital role in modern power system network,right from generation through transmission to distribution end. The currentinterruption device or switching device is called circuit breaker in Switchgearprotection system. The circuit breaker can be operated manually as whenrequired and it is also operated during over current and short circuit or anyother faults in the system by sensing the abnormality of system. The circuitbreaker senses the faulty condition of system through protection relay and thisrelay is again actuated by faulty signal normally comes from currenttransformerorvoltage transformer.

A switchgear has to perform the function of carrying, making and breaking the

normal load current like a switch and it has to perform the function of clearingthe fault in addition to that it also has provision of metering and regulating thevarious parameters of electrical power system. Thus the circuit breakerincludes circuit breaker, current transformer, voltage transformer, protectionrelay, measuring instrument, electrical switch,electrical fuse,miniature circuitbreaker, lightening arrestor or surge arrestor, isolator and other associatedequipment.

Electric switchgear is necessary at every switching point in theelectrical powersystem. There are various voltage levels and hence various fault levelsbetween the generating stations and load centers. Therefore various types of

switchgear assembly are required depending upon different voltage levels ofthe system.
http://www.electrical4u.com/basic-electrical/electrical-hrc-fuse.phphttp://www.electrical4u.com/basic-electrical/electrical-hrc-fuse.phphttp://www.electrical4u.com/basic-electrical/electrical-hrc-fuse.phphttp://www.electrical4u.com/index.phphttp://www.electrical4u.com/index.phphttp://www.electrical4u.com/index.phphttp://www.electrical4u.com/index.phphttp://www.electrical4u.com/index.phphttp://www.electrical4u.com/index.phphttp://www.electrical4u.com/electrical-transformer/current-transformer.phphttp://www.electrical4u.com/electrical-transformer/current-transformer.phphttp://www.electrical4u.com/electrical-transformer/current-transformer.phphttp://www.electrical4u.com/electrical-transformer/potential-voltage-transformer.phphttp://www.electrical4u.com/electrical-transformer/potential-voltage-transformer.phphttp://www.electrical4u.com/electrical-transformer/potential-voltage-transformer.phphttp://www.electrical4u.com/electrical-transformer/current-transformer.phphttp://www.electrical4u.com/electrical-transformer/current-transformer.phphttp://www.electrical4u.com/electrical-transformer/potential-voltage-transformer.phphttp://www.electrical4u.com/electrical-transformer/potential-voltage-transformer.phphttp://www.electrical4u.com/basic-electrical/electrical-hrc-fuse.phphttp://www.electrical4u.com/basic-electrical/electrical-hrc-fuse.phphttp://www.electrical4u.com/basic-electrical/electrical-hrc-fuse.phphttp://www.electrical4u.com/basic-electrical/miniature-circuit-breaker.phphttp://www.electrical4u.com/basic-electrical/miniature-circuit-breaker.phphttp://www.electrical4u.com/basic-electrical/miniature-circuit-breaker.phphttp://www.electrical4u.com/index.phphttp://www.electrical4u.com/index.phphttp://www.electrical4u.com/index.phphttp://www.electrical4u.com/index.phphttp://www.electrical4u.com/index.phphttp://www.electrical4u.com/index.phphttp://www.electrical4u.com/basic-electrical/miniature-circuit-breaker.phphttp://www.electrical4u.com/basic-electrical/miniature-circuit-breaker.phphttp://www.electrical4u.com/basic-electrical/electrical-hrc-fuse.phphttp://www.electrical4u.com/electrical-transformer/potential-voltage-transformer.phphttp://www.electrical4u.com/electrical-transformer/current-transformer.phphttp://www.electrical4u.com/electrical-transformer/potential-voltage-transformer.phphttp://www.electrical4u.com/electrical-transformer/current-transformer.phphttp://www.electrical4u.com/electrical-transformer/current-transformer.phphttp://www.electrical4u.com/index.phphttp://www.electrical4u.com/index.phphttp://www.electrical4u.com/basic-electrical/electrical-hrc-fuse.php


13/25

7. DRAW CIRCUIT DIAGRAM OF SWITCHBOARDMain Switchboard

The main switchboard, as the primary distribution center, distributes 450 volts, 3 phase,

60 cycle power. The 450 volt power is distributed to power panels throughout the ship and

also to the emergency switchboard. Transformers at the lighting load centers step down the

450 volts to 120 volts. The lighting load centers distribute 120 volt power. There are three

lighting load centers. Ships service lighting load centers no. 1 and no. 2 are normally fed

from bus section no. 3.

The main switchboard is composed of three parts consisting of distribution panels at the

right, three generator panels in the center, and distribution panels at the left (facing the

front of the switchboard). Right side distribution and generator no.1 are connected to bus

section 1, emergency switchboard feeder, machinery space lighting and generator no. 2 are

connected to bus section 2. Left side distribution and generator no. 3 are connected to bus

section 3. The three bus sections are normally connected together by removable disconnect

bars.


14/25


15/25

8. EXPLAIN OVERCURRENT AND EARTH FAULT RELAY TEST

In electricity supply,overcurrent or excess current is a situation where a larger than

intended electric current exists through a conductor, leading to excessive generation of heat, and the

risk of fire or damage to equipment. Possible causes for overcurrent includeshort circuits, excessive

load, and incorrect design. Fuses, circuit breakers, temperature sensors and current limiters arecommonly used protection mechanisms to control the risks of overcurrent

Equipment to be used for testing the protection system

Mobile Workstation, Protective Relay Control Station, Transmission Grid A, Interconnection

Module, Universal Fault Module, Power Supply, Faultable Transformer, Resistive Loads,

Current Transformers, AC Ammeter, AC Voltmeter, Three-phase Overcurrent Relay, AC/DC

Current Sensitive Relay, and Connection Leads.

Testing procedure and observations

Ensure that the Protective Relay Control Station is connected to a three-phase power

source. Make sure that the DC Power Supply to the Protective Relay Control Station is

turned off. Also, make sure that all fault switches on the Three-phase overcurrent relay and

AC/DC current sensitive relay are set to O (off) position.

2. Make the following settings on the Universal Fault Module:

TD1 time delay 1 s

SST1 time interval 3 s

SST2 time interval 10 s

(Note: These settings have already been done by the Lab technician)

3. Make sure that the Transmission Grid A, Interconnection Module, Universal FaultModule, Power Supply, Faultable Transformer, Resistive Loads (2), CurrentTransformers, AC Ammeter, and AC Voltmeter are installed in the EMS Workstation. Seethat the Power Supply is turned off and its voltage control knob is set to the O position.

4. On the Current Transformer module, make sure that all the switches are set to the I

(close) position to short-circuit the secondaries of the current transformers.5. Connect the equipment as shown in Figs. 2 and 3.6. Make the following settings:

On the Faultable Transformers

Transformer T1 Fault switches (FS1 to FS3) - - - - - O

Transformer T3 Fault switches (FS1 to FS3) - - - - - O

On Transmission Grid A

Switch S1 - - - - - - - - - - - - - - - - - - - - - - - - - - - - O
http://en.wikipedia.org/wiki/Electricity_supplyhttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Short_circuithttp://en.wikipedia.org/wiki/Fuse_(electrical)http://en.wikipedia.org/wiki/Circuit_breakerhttp://en.wikipedia.org/wiki/Temperature_sensorhttp://en.wikipedia.org/wiki/Current_limiterhttp://en.wikipedia.org/wiki/Riskshttp://en.wikipedia.org/wiki/Riskshttp://en.wikipedia.org/wiki/Current_limiterhttp://en.wikipedia.org/wiki/Temperature_sensorhttp://en.wikipedia.org/wiki/Circuit_breakerhttp://en.wikipedia.org/wiki/Fuse_(electrical)http://en.wikipedia.org/wiki/Short_circuithttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Electricity_supply


16/25

Fig. 2 Connection diagram of the equipment in EMS Workstation

Fig. 3 Connection diagram of the equipment in the Protective Relay Control Station


17/25

On the AC/DC Current Sensitive Relay

INPUT switch - - - - - - - - - - - - - - - - - - - - - - - - - AC

MODE switch - - - - - - - - - - - - - - - OVER CURRENT

On the Universal Fault Module

INITIATE FAULT button - - - - - - - - released position

FAULT DURATION switch- - - - - - - - - - - 0.3 30 s

On the Current Transformer Module

Current transformers CT1, CT2 and CT3 - - - O (open)

7. Set the current set point of the Three-Phase Overcurrent Relay to approximately 200%of the nominal full-load current of the power transformers, taking into account thetransformation ratio of the current transformers.

8. Set the time delay of the Three-Phase Overcurrent Relay to approximately 5 s. Adjustthe set point and hysteresis of the AC/DC Current Sensitive Relay to 100mA and 5%,respectively.

9. Turn on the DC Power Supply of the Protective Relay Control Station.

10.On Transmission Grid A, set switch S2 to O (open) position to open the contactor CR2.This will prevent operation of the protection system and allow the operation of theprotective relays to be observed.

11.Turn on the Power Supply and set the voltage control knob to the 100% position. Setthe primary line current (indicated by ammeter I1) should be approximately equal tothe full-load current of the power transformers by adjusting the resistive loads.

12.On the Universal Fault Module, depress the INITIATE FAULT button to short-circuit onephase of the three-phase load. While doing this, observe the circuit currents andvoltages as well as tripping indicator (red LED) on the Three-Phase Overcurrent Relayand AC/DC Current Sensitive Relay. Record the current and voltages in the blankspaces.

(Note: You may have to initiate this fault a few times to record the circuit currents

and voltages)

I1 = . A I2 = A I3 = A

E1 = V E2 =


18/25

Testing Procedure for Earth Fault Relay (EFR)

1. Record all particulars of relay to be tested and its working settings.

2. Check the auxiliary supply voltage connected to the relay corresponds to the ratedauxiliary voltage stated on its name plate.

3. Connect output of the test set to input terminals of the ELR. Alternatively single-

phase primary current can be injected into one of the conductors to induce a

secondary current on the ZCT

4. Ensure that knob on test set has return to zero position. Then switch on test set.

5. Increase the output current on the test set gradually until relay picks up. Record the

current in test form.

6. Connect a trip contact to timer stop terminals of the test set.

7. Switch on the test set, increase current to 2 times of setting current. Switch off the

test set with control knob remaining in the same position.


19/25

8. Switch on the test set to inject current and start timer at the same time. After trip

contact has operated, record relay operating time in test form. Switch off the test

set.

9. Disconnect all wirings between test set and relay. Check that connection to relay is

normalized.

9. EXPLAIN PREVENTIVE MAINTENANCE

Preventive maintenance (PM) has the following meanings:

1. The care and servicing by personnel for the purpose of maintaining equipment and facilities

in satisfactory operating condition by providing for systematic inspection,detection, and

correction of incipient failures either before they occur or before they develop into major

defects.2. Maintenance, including tests, measurements, adjustments, and parts replacement, performed

specifically to prevent faults from occurring.

The primary goal of maintenance is to avoid or mitigate the consequences of failure of equipment.

This may be by preventing the failure before it actually occurs which Planned Maintenance and

Condition Based Maintenance help to achieve. It is designed to preserve and restore equipment

reliability by replacing worn components before they actually fail. Preventive maintenance activities

include partial or complete overhauls at specified periods, oil changes, lubrication and so on. In

addition, workers can record equipment deterioration so they know to replace or repair worn parts

before they cause system failure. The ideal preventive maintenance program would prevent all

equipment failure before it occurs.

Preventive maintenance can be described as maintenance of equipment or systems before fault

occurs. It can be divided into two subgroups:

planned maintenanceand

condition-based maintenance.

The main difference of subgroups is determination of maintenancetime, or determination of moment

when maintenance should be performed.

While preventive maintenance is generally considered to be worthwhile, there are risks such as

equipment failure orhuman errorinvolved when performing preventive maintenance, just as in anymaintenance operation. Preventive maintenance as scheduled overhaul or scheduled replacement

provides two of the three proactive failure management policies available to the maintenance

engineer. Common methods of determining what Preventive (or other) failure management policies

should be applied are;OEMrecommendations, requirements of codes and legislation within a

jurisdiction, what an "expert" thinks ought to be done, or the maintenance that's already done to

similar equipment, and most important measured values and performance indications.

In a nutshell:

Preventive maintenance is conducted to keep equipment working and/or extend the life of the

equipment.

Corrective maintenance, sometimes called "repair," is conducted to get equipment working again.
http://en.wikipedia.org/wiki/Fault_detection_and_isolationhttp://en.wikipedia.org/wiki/Fault_detection_and_isolationhttp://en.wikipedia.org/wiki/Fault_detection_and_isolationhttp://en.wikipedia.org/wiki/Maintenance,_repair_and_operationshttp://en.wikipedia.org/wiki/Maintenance,_repair_and_operationshttp://en.wikipedia.org/wiki/Planned_maintenancehttp://en.wikipedia.org/wiki/Planned_maintenancehttp://en.wikipedia.org/wiki/Condition-based_maintenancehttp://en.wikipedia.org/wiki/Condition-based_maintenancehttp://en.wikipedia.org/wiki/Timehttp://en.wikipedia.org/wiki/Timehttp://en.wikipedia.org/wiki/Timehttp://en.wikipedia.org/wiki/Human_reliabilityhttp://en.wikipedia.org/wiki/Human_reliabilityhttp://en.wikipedia.org/wiki/Human_reliabilityhttp://en.wikipedia.org/wiki/Original_equipment_manufacturerhttp://en.wikipedia.org/wiki/Original_equipment_manufacturerhttp://en.wikipedia.org/wiki/Original_equipment_manufacturerhttp://en.wikipedia.org/wiki/Original_equipment_manufacturerhttp://en.wikipedia.org/wiki/Human_reliabilityhttp://en.wikipedia.org/wiki/Timehttp://en.wikipedia.org/wiki/Condition-based_maintenancehttp://en.wikipedia.org/wiki/Planned_maintenancehttp://en.wikipedia.org/wiki/Maintenance,_repair_and_operationshttp://en.wikipedia.org/wiki/Fault_detection_and_isolation


20/25

10. DEVELOP A REAL SERVICE LIST AND REPORT


21/25

Inspection Checklist Field Maintenance ReportIdent-Nr.:

Type:

Location / Operator:

General

Date________ Time in ________ Out __________Field Technician(s) _____________________________________

Inspection call 6 / 12 / 18 / 24 / 36 months Regular service Repair of deficienciesRegular Service Sample

Troubleshooting

Plant status

Counter Hours of operation _____________________ [h] Water: _____________________ [gaqPermeate _____________________ [gal]

Accessibility Yes NO System operates Yes NO

Cover free from defects Yes NO System recovers Yes NO

Check Air blower fully functional defect solenoid valve fully functionaldefect

Submerged pump fully functional defect pumping system fully functionaldefect

Level switch fully functional defect pressure increasing fullyfunctional defect

Air-lift pump fully functional defect

Septic / first bufferSoloids sanitary napkins Fat I WaxOther:________________

Odor aerobic septic/fecalsoapily acid

MBR Texture (optically) thin (MLSS


22/25

Functional check pumps & piping aeration

solenoid valvesPermeation Alarm panel

Active carbon filter Check change of cleaning

Remarks:

_____________________________________________________________________________________

_____________________________________________________________________________________

_____________________________________________________________________________________

___________________________ ________________________BUSSE Innovative System GmbH Customer/Operator


23/25

This Equipment Schedule is provided as an example only. Refer to Section 26 29 90B and

Section Cover Sheet for details.

Equipment Make Model Quantity

Power Transformer, Dry Type

Switchgear Enclosure

Low Voltage Air Circuit Breakers

Fused LB Disconnect Switchgear

Unfused LB Disconnect Switchgear

Fused NLB Disconnect Switchgear

Unfused NLB Disconnect Switchgear

Induction Disc Relays

Overcurrent Relays

Solid State Relays

Overhead Power Line Insulators

Overhead Power Line Connectors

Overhead Power Line Wooden Poles

Overhead Power Line Metal Tower Structure

Surge Arrestors


24/25

RECOMMENDED MAINTENANCE SCHEDULEThe Bandsaw is not a high maintenance machine, and it is strongly suggested thata programmed maintenance schedule is developed for this equipment and that timeis allocated specifically for maintenance purposes.

The table below is offered as a guideline.

To add another entry to the table, place your cursor in the bottom last column celland go to Table > Insert > Rows below or above the placed cursor cell.

Machine ID: eg. B.S. wood/metalRoom ID:

Maintenance Operation Daily Weekly

Check Switch gear and examine for observable defects. *

Check Electrical wiring for visual damage. *

Check push sticks and similar are available and in goodrepair.

*

Check guards for security and correct operation. *

Check availability and condition of personal protectiveequipment.

*

Check condition of workspace/walk ways and ensureworkspace is clearly defined.

*

Check blade guides for correct operation. *

Examine blade for cracks, deformities and broken teeth. *

Check inventory of spare parts to ensure spare blades etc.are available.

*

Lubricate Machine according to manufacturers specifications.Daily or before

use


25/25

Report Siap Explain Switchgear and Switchgear Maintenance

Documents

Transcript of Report Siap Explain Switchgear and Switchgear Maintenance