Circuit Breaker Contact Resistance Measurement Test

Stationary and moving contacts are built from alloys that are formulated to endure the abuse of electrical arcing.  However, if contacts are not maintained on a regular basis, their electrical resistance due to repeated arcing builds up.  This resistance build-up results in a significant decrease in the contact’s ability to carry current.  Excessive corrosion of contacts is detrimental to the breaker performance.  One way to check contacts is to apply dc current and measure the contact resistance or voltage drop across the closed contacts.  The breaker contact resistance should be measured from bushing terminal to bushing terminal with the breaker in the closed position.  It is recommended that for medium and high voltages the resistance test be made with 100-Amps (or higher) direct current.  The use of a higher current value gives more reliable results than using lower current values.  The resistance value is usually measured in micro-ohms.  The average resistance value for 15-kV-class air circuit breakers is approximately between 200-250 mico-ohms.  The evaluation should be made on comparing resistance values of the three phases with each other, or with resistance values of similar breakers.  A difference of more than 50 percent in resistance values among the three phases of a breaker should warrant further investigation.

Whether your needs are as simple as contact resistance testing or more advanced requiring a full regiment of breaker tests including First Trip, Protec Equipment Resources has a full inventory of micor-ohmmeters from Megger DLRO, Raytech, Vanguard and AEMC along with Circuit Breaker Timer Analyzers from Vanguard and Doble.

Comments for Circuit Breaker Contact Resistance Measurement Test

Name: shaheen
Time: Thursday, December 22, 2011


Name: Shashikant P Padhye
Time: Sunday, January 8, 2012

pls. Quote Price & Delivery structure for CRM Tester of 10Amps & 100Amps.
Thanks & Regards. S.P.Padhye
Energy Systems
+91 0 9820216448
+91 09819781558

Name: yasser ali
Time: Wednesday, March 28, 2012

how to measure contact resistance

Name: danielmontero
Time: Wednesday, May 9, 2012

Acceptance result for the indoor plug-in breakers rated 15-100 ampers

Name: avijit Poddar
Time: Sunday, May 13, 2012

Show me the video of contact resistance measurement for LV & MV Breaker

Name: saied
Time: Tuesday, May 15, 2012

i want measurment resistancce for type of breakers 33kv,132kv,230kv,400kv ieee

Name: harsukh
Time: Sunday, June 3, 2012

masurment mathod of contect resitance of ht bkr

Name: ram gopal
Time: Saturday, July 21, 2012

sir i want to conduct test to measure contact resistance so please send paper for reference

Name: Satheesh
Time: Monday, July 23, 2012

Why we are doing contact resistance measurement.

Name: prachand jang shah
Time: Tuesday, August 28, 2012

sir, can u send me the test report of normal 145 KV breaker of DCRM test, if it s possible than send me in above mail address.

Name: Kaseer
Time: Sunday, October 7, 2012

145 kV busbar circuit Contact resistance taest ia scheduled, so please send any reference documents for BB & CB

Name: Hardik Zinzuvadiya
Time: Sunday, January 20, 2013

sir, can u send me manual type material for breaker DCRM testing in which total procedure included like how to make kit wiring with breaker and how to take test?

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