Manual RMO-H
M-RH00NN-300-EN
11
3.3 Connecting RMO-H to Both Sides Grounded (BSG) Circuit Breaker
The RMO-H device provides a safer measurement approach to the breakers with both terminals
grounded. The connection method for both sides grounded circuit breakers is the same as for one side
grounded circuit breakers. This type of a measurement could provide less accurate results comparing to
a traditional one side grounding measurement, because of a small amount of current that can flow
through groundings. The inaccuracy depends of the resistance of the grounding loop. The measured
resistance of the circuit breaker mains contacts can be corrected if the resistance of the grounding loop
is known (or measured). The procedure is described in Application Note originally published by DV
Power (IBEKO Power AB) in Year 2011:
“Main contact resistance measurement of a Circuit breaker with
both sides grounded (BSG)”
.
The connection diagrams of the RMO-H device applied to both sides grounded circuit breaker is
presented in the following figure.
1. Short test leads (current and voltage sense cables labeled with red color)
2. Longer test lead (current and voltage sense cables labeled with black color)
3. Ground cable
4. Ground cable (used in case of Both Sides Grounded testing)
NOTE:
The connection diagram for measurement in Both Sides Grounded
conditions is the same as for one side grounded circuit breaker.
Figure 3-4:
Connecting RMO-H
to both sides
grounded CB
