MCC and Panels Maintenance Procedure

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MCCP and Control Panels Maintenance Procedure

MCCPs, CPs, and Miscellaneous Motive Drive Panels

Introduction

When working on or testing Control panels it is essential that all local and national statutory regulations should be observed at alltimes. In the United Kingdom the Health and Safety at Work Act 1974, and the Electricity at Work Regulations 1989 areparticularly relevant. It should be noted that control panels having equipment operating above a nominal 415 Volts are excluded

from this specification. This does not imply that safety precautions should not be taken when working on equipment above 415volts.

Care should be taken to make sure that all remote circuits associated with the switchgear are positively isolated before any workis carried out. The isolation should be secure, that is it should either be at the point of work or precautions should be taken toprevent anyone else switching on again when work is in progress. A circuit, whether power, or control, should never be assumedto be dead. Voltage test should always be carried out with proven test equipment, i.e. a voltage tester should first be checkedon a known live source immediately before use and again after use.

Whenever cables are disconnected from switchgear in the course of maintenance or replacement, ensure that the cables aresuitably insulated and marked for identification for reconnection.

Visually inspect to ensure plant is operating as expected. Check that any meters fitted show correct reading, and any timers areset at the correct times for operation. Check readings against a known source.

Controllers, electrical and pneumatic cont rol equipment

Electronic controllers and pneumatic equipment may be found in control panels and details regarding maintenance schedulescan be found in the appropriate sections of this schedule.

Appropriate safety guides are as follows:-

HSE Guidance Notes

Doc Ref: TE/822/902Page 1 of 15


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HSG)D38 - Electrical test equipment for use by electricians.HS(G)12 - Safety in Electrical Testing.HS(R)25 - Memorandum on Guidance on the Electricity at Work Regulations 1989.



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Control panel electrical services (excluding electrical controllers and pneumatic relays)

Before commencing any maintenance work on control panels; read the notes in the Control Panels introduction very carefully, andfollow all the safety procedures.

ITEM FREQ ACTION NOTES

1. Panel exterior. 3m Check for physical or mechanicaldamage. Door locks should bechecked.

Any damaged equipment mounted on the front should bemade safe and replaced as soon as possible. Locks shouldbe checked for correct security and locking arrangements.

2. Mains isolator (alsocubicle isolator)

6m Inspect for correct mechanical andelectrical operation. Lubricate anymoving parts as required. Checkcorrect operation of the doorinterlock mechanism and adjust if

necessary. Clean out interior.

Physically check for security all mains connections.Examine both fixed and moving contacts for wear orpitting.

Use only Manufacturers recommended lubricants. Redress

or replace contacts according to the manufacturersinstructions.

Ensure that any mains shrouding is refitted after thecompletion of the work.

3. Fuses. Ensure circuitsare dead before carrying

out actions.

6m Inspect fuse carrier/fuse holder forsigns of over heating. Check fuse

rating and terminations fortightness. Apply grease to fuseholder if required.

Replace if necessary and establish cause of over-heatingand rectify.

Value of fuse should be checked against the circuitapplication and electrical load.

4. Circuit breakers. 6m Inspect for signs of over-heatingand replace if necessary. Inspectconnections and tighten ifnecessary. Check operation bytripping or test facility, if fitted.

Establish cause of overheating and rectify.

Ensure value of breaker corresponds with circuit applicationand electrical load.



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5. Residual current devices. 6m

12m

Test operation using test facility.

Carry out electrical test proceduresper IEE Regs

6. Power contactors 12m a) Check contact for correctmechanical and electrical

operation.b) Strip and clean interior.c) Inspect and clean magnetic pole

faces. Inspect shaded ring fordamage and fixed and movingcontacts for wear or pitting.

d) inspect coil for over-heating orinsulation breakdown.

e) Clean out arc-shutes. On re-assembly: avoid damage orloosening of springs or contacts,ensure correct mechanicaloperation and check all electricalconnections for tightness andsecurity.

Damage contact should be redressed or replaced asnecessary.

Use approved contact lubricant if recommended by themanufacturer. (where fitted)

Spring and contacts should be correctly positioned andseated.

1. Starters star delta two speed - dual wound two speed - pole change reversing auto transformer

12m Carry out maintenance as for powercontactors.

See maintenance details below



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quick transition, electricheater and electrolytetypes.

8. Thermal overloads 12m a) Inspect for signs of overheating.b) Check electrical connections for

tightness and security.

c) Inspect trip settings.d) Operate the trip/test facilityensuring that the switchgear de-energises in a clean and positiveoperation.

Replace if necessary after having established the cause andrectified it.

Adjust if necessary to give correct protection for theconnected load. Record settings.Check for single phasing protection by operating the starterwith one of the power fuses removed.

9. Magnetic overloads. 12m a) Inspect for signs of overheatingb) Check electrical connections for

tightness and security.

c) Check oil levels in dashpots andreplenish to correct levels ifneeded.

d) Check time mechanism.e) Operate test facility ensure

switchgear de-energises in aclean and positive operation.

f) Inspect trip settings.g) Check single phase protection

Completely replace dashpot oil at intervals recommended bythe manufacturer.

Select correct dashpot drain hole if necessary.

Adjust if necessary to give correct protection for connectedload.This is done by operating starter with one of the power fusesremoved.

10. Busbar systems. 12m Isolate supplies, inspect for signs oroverheating, damage or burnt outcables inspect mechanical supportsystems and adjust fixings ifnecessary.

Check all cable crimps for security and fraying. Inspectcrimp fasteners for correct torque rating.



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11. Incoming powersupplies.

12m Measure each line to earth andeach line to neutral.

Record reading and check that measured values are withinelectricity suppliers specification.

12. Panel wiring 12m a) Inspect for signs of overheatingor burn marks.

b) Replace any suspect conductors.c) Check all connections,

terminations, earth cables andlinks for security and tightness.

d) Ensure cable connections aretight and correctly terminated.

e) Check that panel is correctlybonded to earth.

Test continuity and record readings.

13. Flash test. 36m Carry out within 1.5kV-3.0kV rangeto detect potential deterioration of

the system.

CAUTION - Care should be taken to isolate sensitiveequipment.

Star / Delta Starters

1. Switchgear. 12m Carry out maintenance proceduresas per power contactors.

2. Interlocks. 12m Inspect and check both electricaland mechanical interlocks betweenStar and Delta contactors.

3. Start up sequence. 12m Check for correct sequence fromstart up. Inspect, check and adjustsetting of timer to match characterof the connected load.

Star first then Delta mode.

4. Starter overload settings. 6m Check. If overload is connected into the Delta loop the overloadshould be set at 0.58 of the line current.

Starters: - Two speed - Dual wound



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1. Switchgear. 12m Carry out maintenance2. Interlocks. 12m Inspect and check both electrical

and mechanical interlocks betweenhigh and low speed contactors.

3. Timers. 12m Check and set. Timers should be set between high and low and low tohigh operation to match the characteristics of the connectedloads.

4. Overloads 6m Check both high and low overloads. Overloads should be set to give the correct protection to theconnected loads.



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Starters: - Two speed - Pole change

1. Switchgear. 12m Carry out maintenance proceduresas per power contactors.

2. Interlocks. 12m Inspect and check both electricaland mechanical interlocks betweenthe loop and star (high)

contactors.3. Timers (if fitted) 12m Check and set. Timers should be set between high and low and low tohigh operation to match the characteristics of the connectedloads.

4. Overloads. 6m Check both high and low overloads. Overloads should be set to give the correct protection to theconnected loads.

Starters: - Reversing

1. Switchgear. 12m Carry out maintenance procedures

as per power contactors.

2. Interlocks. 12m Inspect and check both electricaland mechanical interlocks betweenthe forward and reverse starters.

3. Timers (if fitted). 12m Check and adjust between the twomodes of operation to suit theapplication.

Inspect and check that the drive is operating in the correctdirections.




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Starters: - Auto-transformer1. Switchgear. 12m Carry out maintenance procedures

as per power contactors.

2. Interlocks. 12m Inspect and check both electricaland mechanical interlocks between

the main transformer load, the loadand the transformer by-passcontactors.

3. Timers (if fitted) 12m Check and adjust the timer settingbetween the transformer load andby-pass contactors to suit theconnected load.


5. Transformer. 12m Inspect and check for signs ofoverheating.



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Starters: - Quick transition, electric heater

1. Switch gear. 12m Carry out maintenance proceduresas per power contactors.

2. Interlocks. 12m Inspect and check both electricaland mechanical interlocks betweenthe main run and transitioncontactors.

3. Sequence timers. 12m Check and adjust to suit thecharacteristics of the connectedload.

4. Overloads. 6m Check and set to give correctprotection for the connected load.

Electric Heater Type1. Electrical connections. 12m Check.

2. Heater elements. 12m Inspect for signs overheating orelement breakdown.

Replace as necessary.

Starters: - electrolyte types

1. Liquid level. 12m Check level and replenish as



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required.

2. Specific gravity. 12m Check against manufacturersvalues.

Follow manufacturers maintenance instructions.

Control Relays

General1. Mechanical wear. 12m Inspect for excessive wear.

2. Contacts. 12m Check for wear, redress or replaceas required.

3. Coil. 12m Inspect for signs of over-heatingand insulation breakdown.

4. Electrical operation. 12m Operate relay and check for cleanoperation of each set of operations.

5. Pole faces. 12m Clean if noisy operation of relay.

Plug in type

1. General maintenance. 12m Carry out as per instructions givenabove.

2. Relay connection pins. 12m Inspect for signs of burning. Replace relay if necessary.

3. Base unit. 12m Inspect for signs of overheating orarcing.

Replace base unit if necessary.



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Mercury switches1. Mercury bulbs. 12m Inspect and check mechanical and

electrical operation.

2. Connections to bulbassembly.

12m Inspect for wear, assembly,breakdown of insulation, or frayingof connections.

Latch type1. General maintenance. 12m Inspect and check mechanical and

electrical operation.2. Latched states. 12m Check the mechanical and

electrical operations of both latchedstates.

Selector Switches and Push Buttons

1. Operation. 12m a) Inspect and check bothmechanical and electricaloperation.

b) Operate to ensure a free andclean movement in its action.

2. Contacts. 12m Inspect for any signs ofoverheating, pitting or wear.

Replace as necessary.

3. Application. 12m Check switch/push button forparticular application.

Panel lamps, meters, alarms, etc

Indicator lamps.



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1. Circuit. 1m Check and energise to ensure thatthe indicator is operational.Replace any blown or discolouredbulbs as required.

Replacement bulbs should be of the correct type and thevoltage and power rating must be as per themanufacturers specification. A device of a higher powerrating should not be used.

2. Holder assembly 6m Inspect for signs of overheating orelectrical burn marks.

3.Mains/low voltagetransformer(if fitted)

6m Examine for signs of overheating orinsulation breakdown.

Low voltage power packs - ac or dc types.1. Condition. 12m Inspect for signs of over heating.

2. Voltage input and outputtests.

12m Carry out and compare withmanufacturers tolerance andoperational specifications.

Check polarity of outputs where necessary.

3. Load measurements. 12m Carry out, record and ensure thatthe load taken from the unit is withinthe manufacturers specification.

4. Associated safety or tripdevices.

6m Check for correct operation.

Metering (Voltmeter)1. Instrument. 6m Inspect and check for correct

mechanical and electrical operation.Check actual reading, record and compare with areference voltmeter applied across the same circuit.



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2. Needle (pointer). 6m Check for free and correctmovement.

3. Zero setting. 6m Check and adjust if necessary.

Metering (Ammeter)

1. Instrument. 6m Inspect and check for correctmechanical and electrical operation.

Check actual reading, record and compare with areference ammeter applied in series in same circuit.

2. Needle (pointer). 6m Check for free and correctmovement.

3. Zero setting. 6m Check and adjust if necessary.

Alarm integrator1. Operation. 12m Inspect and check operation of

each input channel.

2. Audible and visualalarms.

12m Check operation and indicationsincluding alarm circuits if fitted.

Smoke alarm unit1. Unit. 12m Inspect; check operation by

adjusting or operating alarm test

facility (if fitted).

2. Alarm setting. 12m Reduce setting and note operationof smoke condition.

3. Maintenance. Carry out manufacturers testingand maintenance procedures asrequired at stipulated frequencies.



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Ventilation1. Grilles. 3m Inspect and check that all grilles are

free of any obstructions, clean asrequired.

2. Fans (forced ventilation). 3m a) Inspect and check operation offan unit;

b) Clean and replace filter unit asrequired.

3. General 6m All power and control circuits shouldbe checked for functional operationagainst the wiring diagramsrelevant to the installation.


MCC and Panels Maintenance Procedure

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