Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 7 replies
  • Subscribers 32 subscribers
  • Views 715 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

How to prove an MCB functions correctly?

Paul Brewerton
Is there any way of proving that an old Crabtree C50 MCB functions correctly?

Modern equipment comes with certificate of conformity and is traceable, but we are having to use an old breaker in an old board, and would like some confidence that it is actually fit for purpose.

TIA
Parents
  • 0
    Testing this sort of kit is not trivial, largely because of the difficulty of measuring the current when it flows for a very short time.

    If you ramp up the current slowly enough to read the meter, the thing will probably trip on thermal first. If you set up a circuit which carries a given high current then add the MCB, the circuit resistance will change and so will the current. Yes, given an oscilloscope or constant current circuits it can be done.

    I had a lot of fun many years ago at Inverkip power station proving that an MCCB was being very erratic, the instantaneous trip would sometimes trip on one current and at others not trip at more that twice that current.
Reply
  • 0
    Testing this sort of kit is not trivial, largely because of the difficulty of measuring the current when it flows for a very short time.

    If you ramp up the current slowly enough to read the meter, the thing will probably trip on thermal first. If you set up a circuit which carries a given high current then add the MCB, the circuit resistance will change and so will the current. Yes, given an oscilloscope or constant current circuits it can be done.

    I had a lot of fun many years ago at Inverkip power station proving that an MCCB was being very erratic, the instantaneous trip would sometimes trip on one current and at others not trip at more that twice that current.
Children
No Data

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines