BigBill53
Electrical
- Dec 9, 2010
- 35
Hi,
I have an old resistive starter that has been overhauled. We installed 8 new 250A contactors, all with 240VAC coils. When we were testing the starter the main RCD to the board would trip when the third contactor turned on. It should be noted that we did not have the motor connected at this time - we were simply testing the starter to see if all the contactors came in at the right time.
Well, we didn't really know why this was happening so we jacked up the settings on the RCD temporarily (up to 1000mA for 3 seconds). Now we can get the 7th contactor to come in before the RCD trips.
This has me baffled. Why is the RCD tripping? Everything runs fine when the RCD isn't connected. We have to leave the RCD connected though because of a directive from the mines inspector (I won't get into that now though).
I have an old resistive starter that has been overhauled. We installed 8 new 250A contactors, all with 240VAC coils. When we were testing the starter the main RCD to the board would trip when the third contactor turned on. It should be noted that we did not have the motor connected at this time - we were simply testing the starter to see if all the contactors came in at the right time.
Well, we didn't really know why this was happening so we jacked up the settings on the RCD temporarily (up to 1000mA for 3 seconds). Now we can get the 7th contactor to come in before the RCD trips.
This has me baffled. Why is the RCD tripping? Everything runs fine when the RCD isn't connected. We have to leave the RCD connected though because of a directive from the mines inspector (I won't get into that now though).