switchgear maintenance 1

I am currently trying to set up a maintenance schedule for circuit breakers in a medium size plant (10 Mw) with different types of equipment,could some one please suggest some handy tips to achive my goal.

 

[wbd]

Read the tech manual that comes with the eqpt. It should give you a good starting point which may have to be tempered by experience and operating conditions. For example, if the eqpt is exposed to adverse environment (heat, dust,etc.) and sees alot fault interruption.
Probably, the minimum:
Infrared inspection - yearly
Inspect bkr contacts, grease, loose hardware, arc chutes (if any) - yearly to 2 yrs
Bus work - every 5 yrs, clean and check tight all connections, visual for overheating
Relays- every 2 yrs, calibrate

This should get you started.

Barry

 

[eiectrical]

Thanks barry i have tried the tech manuals but i what to test the circuit breakers with current injection by means of a AVO meggar current injector the cb is a mitsubishi ACB (AE1600-SS) ther are also merlin gerlin cb .
what is the correct type of bolts to be used when connecting the busbar to the breaker ? I was thinking 8.8high grade steel with lock washers

 

[shaq]

Yes,i am also intrested in switchgear mainteince.I am also intrested in current injection

 

[hy]

I would like to know the voltage of the CBs

 

The voltage of the cbs is low voltage 1000v-50v RMS ,typicaly Vl 400v and Vph is 230v
and if any one know the meaning in lay man terms of these terms from a mitsubish cb

(1) % lu
(2) ln max
(3) lu X Ic
(4) STD P.U ls xlu
(5) lcs/lcu

thanks paulryan1

 

[PowerSaudi1]

before starting the schedule setup, you have to consider the follwing:
1- the switchgear consists of circuit breakers, the bus, relays, earthing switches, (and might have disconnect switches) control panel and annunciator panel. The maintenance should include all these.
2- set the frequency and lenght of maintenance for each device. For example, the circuit breaker have to be maintaned for 6 hours every 3 years (this is only a generic example).
3- try to link all associated devices in the same maintenance outage, so that you will reduce equipment outage.

 

[wbd]

Good Morning,
I can't help with the terms your looking for, perhaps there is an IEC document that has standard definitions.
For the bolting, I would use stainless steel, also if you are bolting two dissimiliar metals together (aluminum to copper), you need to use a transition plate in between.

 

[redtrumpet]

National Electrical Testing Association (NETA) is an ANSI-accredited standards developer and they may have maintenance schedule recommendations for switchgear. I know they have field acceptance and maintenance testing procedures for switchgear. Try checking with your local electrical test/service firm. They usually have maintenance schedules for switchgear, and if they are NETA-certified they can tell you the NETA recommendations.

 

[ECHU]

FOR THE TYPE OF MITSUBISHI ACB, THE OCR TEST SHOULD BE CARRIED OUT BY THE BREAKER TESTER "TYPE Y-2000" FROM THE MANUFACTURER.

THE MEANING OF TERMS AS FOLLOWS:
1. % IU -- PERCENTAGE OF UNINTERRUPTED CURRENT
2. % IN MAX -- PERCENTAGE OF THE RATE CURRENT OF THE ACB
3. IL -- LONG TIME DELAY CURRENT
4. STD P.U IS X IU -- SHORT TIME DELAY CURRENT IN MULTIPLE OF IU

ALL OF ABOVEMENTIONED INFORMATION CAN BE READ FROM THE O&M MANUAL OF THE ACB TESTER.

PLEASE ALSO NOTED THAT YOUR PRIMARY INJECTION TEST MAY NOT BE CAPABLE TO TEST THE SHORT TIME DELAY FUNCTION.

 

[bmodrow]

paulryan1 I think that wbd has given a very good response for starters I would however make the following addition.

Inspect bkr contacts, grease, loose hardware, arc chutes (if any) - yearly to 2

I would suggest performing primary injection testing at the same interval you perform your breaker maintenace. This will ensure that your trip units, cts, and trip circuits are functioning as intended as well as the mechcanical aspects of the breaker and that the breaker operates as designed.

Many people prefer to perform secondary injection testing only instead of primary injection. Secondary injection testing is fine when you want to know if your secondary trip device itself is functioning but in most cases it does not test the entire breaker trip circuit or the mechanical action of the breaker and can lead to a false sense of security.

 

[GusD]

Hello paulryan1

In addition to the info provided by the previous posts,I would try to make the switchgearIR friendly.(Infrared Mon)
For about 7 years now,we have been designing our new HI/MEDvoltage gear with special IR windows and retrofitted
some of the older Sgears as well.
These non intrusive devices, are a of relative low cost and if they are placed at stratigically critical areas of the swichgear, they will give good rewards for the life of the switchgear.If you can perform IR scanning ,it may very well help in determining how often should you do maintenance in your sgear.
Quite often,schedulled maintenance work will introduce faults to the systems ,that were not there before.
There are some maintenance tasks, that have to be prformed and a lot of that depends on the type of installation or processes.If your HV breakers are subject to a lot of heavy duty trips,it will require some serious maintenance,regardless of anything else.


GusD

 

[aali2208]

Paul Ryan/Shaq,

I have been in the Installation & commisssioning of LV/MV/HV Switchgears for About 9 Years, We Normally Check the following for LV & MV Equipments and I believe this will give you very good idea about the health of your Equipment
Visual Checks:
Any Deformation of Fix/ Moving Contacts, Decolouration, Arcing Etc.
Insulators/ Drive Arms conditions, (Any Roughness/Damage on Insulator Surface must be Checked)
If this is the first PM after Installation You Should also verify all the connections on Bus Bars/Breaker IN/OUT Terminals,
In case Of OCB/VCB/Gas insulated Eq. Check the contact Resistance across Switching device, In case of Air Insulated Equipment you can have the contact Print on White Paper.
Primary Injection Test is only needed for the first time to ensure the Circuit Integrity and if some modifications or repairs have been done in Primary/ Secondary side of the equipment. For Breakers You can do it repeatidly if the Protection is built-in and have no Option for any test Device to connect irectly to the Protection Module.

Secondary Injection is recommended each after 2-3 years or in case of Fault in the Equipment (Malfunctioning of Protection Relay, Recaliberation, Re configuration of Digital Relays etc).

Hope this will be helpful for you in scheduling the PM,
In case you want more detail please contact again

AALI