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What are the differences between the ENVT and ENCT?

Issue:
What is the purpose of the ENVT and ENCT?
 
Product Line:
Circuit Breakers
 
Environment:
ENVT - Powerpact H, J and L breakers with Energy Trip Units
ENCT - Powerpact H, J and L breakers with Ground Fault Trip Units

 
Resolution:
The ENVT and ENCT serve very different purposes.
  • The ENVT involves a measurement of phase-to-neutral voltage
  • The ENCT involves a measurement of load current current
The following is a more detailed explanation.

ENVT
The ENVT is used to measure phase-to-neutral voltage on systems that have a neutral (such as 120/240Vac, 208Y/120Vadc, 480Y/277Vac). That phase-to-neutral voltage, along with the phase-to-phase voltage and amount of load current already measured an Energy Trip Unit in the breaker, is used provide functions involving measurements of voltage, power, and energy. In the breaker, the ENVT consists of 1 long white wire that is factory connected to the trip unit, and field connected to the system neutral bus. See the picture below of a breaker with the ENVT wire. (Note that if the voltage system does not have a neutral, or voltage measurements are not required, the ENVT wire can be capped off and not used.)


ENCT
The ENCT is used to measure load neutral current on solidly grounded systems (such as 120/240Vac, 208Y/120Vac, and 480Y/277Vac). That load neutral current, along with the phase current already measured by the Ground Fault Trip Unit in the breaker, is used to provide equipment ground fault protection. In the breaker, the ENCT wire harness consists of 2 wires field or factory connected to trip unit terminals T1T2, and field connected to neutral CT terminals T1T2. See the picture below of an ENCT wire harness. (Note that if the breaker has the ENCT wire harness, but no neutral CT is required for the load, it is OK to remove the wires from trip unit terminals T1T2 as long as a jumper is then installed between the terminals.)



See the below for schematic diagrams comparing the ENVT and ENCT.
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