Switchgear Circuit Breaker Tests

Are yopu asking what testng is performed by the breaker manufacturer when the breakers are made? Or are you asking what sort of testing should be performed as routine maintenance on breakers once they are already installed in switchgear in the field?

By manufacturer

It depends on the manufacturer. Some do individual testing, some do not (on low voltage systems) but instead opt for "batch testing" where a few breakers from each production run are tested. Larger Air Break / Insulated Case Power Breaker systems tend to get individual testing however. The breakers are tested and calibrated using current injection, then the entire assembly is given a hi-pot test at the very least. There are standard ANSI tests applied at a minimum, some do more than the minimum.

Requesting permission from JRAEF, may i amplify a bit ...

As per IEC (and i am sure similar clauses exist in US standards), the manufacturer has to do (a) Type tests to prove that the CB is capable of making and breaking short-circuit currents, and also a slew of overload and normal load performance requirements, mechanical life, hipot tests etc. and (b) Routine tests to ensure that each CB manufactured will perform as designed. Good manufactureres also do 'Audit' tests on random samples out of production lots to ensure that no slippage of quality has occurred, and that the CB will do all type tests ok.

Hi,

let me ask about routine maintenance testing - scope and timing - for HV and LV switches -

ones in year at least

- visual inspection

- Thermography

- Utrasonic Inspection

ones in... around 5 years

- Insulation resistance test

- Contacts resistance

- Electrical/mechanical testing/adjustment/cleaning etc.

- protective devices testing

seems to be like this but, do not sure it is full list of tests and - how correct is my "around 5 years"

i would recommend your 5 yr things as 1 year, and some thermography (using non-contact Raytheon type thermometers) on a more frequent (montly) basis. You see, most problems in switchgear come because of poor terminal connections. So, as long as your terminal temperature is ok, most probably, the switchgear will be ok too. However, if it is ON for a long time, some mechanical creep may set in, trip-latches may seize in position, and when a command comes to make the Circuit breaker trip, it may not. Prudent to check this periodically.

i must qualify that i am a design engineer of LV switchgear, and have no real experience in HV as well as in maintenance.

well, thank you

it would be nice to check all yearly, but it is hardly possible - long plant shut down when we can accept power outage is planned ones in 15-18 months only. Another point is a cost - to do complete test of MV Switchgears is expensive enough -(

Yes, i appreciate the difficulty of frequent checks. However, there are on-line testing equipment which claim the ability to test all critical parameters of circuit breakers in a live switchyard. i am not sure how it works, maybe you can talk to the supplier ... here is one from India.

http://www.scopetnm.com/HISAC.htm

They claim that you can do all the following tests:

•	Universal CBOA to test all types of CBs – LV, HV & EHV
•	Quick performance check of CB by measuring C, O, C-O, O-C & O-C-O timings with resolution of micro-seconds and selectable delay between multiple operations
•	Saves down time & number of operations of CB by testing all the critical performance parameters of all the poles / breaks in a single shot
•	Indicates pole to pole and break to break operation times for CBs having up to 4 main & 4 PIR contacts per pole, all 3 poles simultaneously
•	Simultaneity of operation of breaks and possibility of pole discrepancy can be assessed
•	Estimation of severity of condition of arcing tip through measurement of number & duration of bounces / chattering
•	Condition assessment of Auxiliary contact by measuring Auxiliary contacts timings (Wet & Dry contacts simultaneously) – input for auxiliary contact setting to obtain specified C-O time
•	Condition of Close / Trip coils of all three poles monitored simultaneously
Minimum current required for CB operation – point of plunger displacement Maximum current drawn by coil Duration of current passing through coil – auxiliary contact cut off time
•	Analysis of Travel Characteristic with customised Travel Transducer cum Fixtures
Velocity of breaker contact / mechanism of three poles simultaneously Velocity at the instant of make or break as well as velocity in between user specified points Contact gap, contact wipe or insertion, over travel & rebound Condition assessment of the damping mechanism
•	Dynamic Contact Resistance Measurement for condition monitoring of the contacts without opening the interrupter
Option for simultaneously recording DCRM signature of single or multiple (up to 6)* interrupters Independent, isolated, inbuilt 100A DC sources for single or multiple (up to 6)* interrupters – still highly portable When DCRM signature is co-related with travel curve, the condition of main and arcing contacts can be assessed and wear & tear of arcing contacts can be estimated
•	Monitor Station Battery Voltage (DC)
•	Measurement of ohmic value of PIR
•	Test results downloaded directly to PC/Laptop or hand held Memory Bank$
•	Operation*, PC downloading, analysis & data manager software
Self navigating, high level Graphical User Interface Programmable Test Plans* facilitating creation of Test Setup Library* – reduces testing time & involvement of valuable manpower Automatic creation of directory structure for storage of test data
•	Eliminates errors associated with manual data storage
•	Easy future retrieval
•	Trend analysis made easy
Dynamic calculations on graphical information with cursor movement facilitating easy on-screen analysis Multiple signature comparison and Trend analysis enables present condition assessment and prediction of future performance
•	Comparison of test result with Manufacturer's test result through programmable limit checks
•	Trend analysis enables a shift from schedule-based maintenance to Condition based, thus reducing outage required for testing
•	Easy to use – self guided operation through interactive menu & keyboard$ or through PC with customized test plans*
•	Designed to work reliably under live EHV switchyard conditions ensuring operator's safety and repeatability of results
•	Totally modular construction, conforming to DIN standard, offers expandability through addition of modules to meet testing needs of future*
•	Lightweight, housed in rugged aluminium case$ enhancing transport worthiness
•	Trolley mounted arrangement* facilitates easy movement within switchyard
•	Printing of tamperproof customized test reports
•	Supplied with test lead set having quick-fit connectors, suitable for EHV CBs
•	Can be ordered as CB Operational Analyser - basic version or with accessories/modules like customized Travel Transducer-cum-Fixtures, Dynamic Contact Resistance Measurement module, facility of PIR value measurement & Station Battery Voltage measurement etc.

thank you, kvsridhar,

will study this and than come back with another questions - the deeper you study a matter the more questions you have. And pass my the best to India - I did spend nearly four years over there -))