IS-NT-Async-SPI, SW Version 1.2,   ©ComAp – February 2011                                
IS-NT-Async-SPI-1.2.PDF 
 
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Binary outputs – Breaker control 
GCB close/open  
The output controls the generator circuit breaker. It is intended for contactors – provides a continual active 
signal if GCB should be closed. 
GCB ON coil  
The pulse output for GCB closing. If GCB synchronizing is enabled, the pulse length is 2s, if not, pulse length 
is 5s. 
Hint:
 
ON coil can only be closed if UV coil is already active for at least 1s and MinStab time has elapsed. 
GCB OFF coil  
The pulse output for GCB opening. If GCB synchronizing is enabled, the pulse length is 2s, if not, pulse 
length is 5s. 
GCB UV coil  
GCB undervoltage coil. Output is closed if generator values are within limits and GCB is ready to be closed. 
It is opened if GCB should be open, and then closed again if generator electric values are in limits. If GCB 
synchronizing is enabled, the opening pulse length is 2s, if not, pulse length is 5s. 
Hint:
 
UV coil automatically opens and OFF coil closes if GCB is closed spontaneously, not from controller’s 
activity. This state lasts until the GCB status has been deactivated. 
The only exception is during synchronization state, as an external device is allowed to close the GCB. 
GCB status  
Indicates breaker state expected by controller (based on gen-set state, controller commands and breaker 
feedback). Can be used for external indication of breaker status according to controller’s information. 
MCB status    
Indicates breaker state expected by controller (based on breaker feedback). Can be used for external 
indication of breaker status according to controller’s information. 
Neutral CB C/O  
Neutral circuit breaker close /open output controls the generator Neutral circuit breaker. It is intended for 
contactors – provides a continual active signal if NCB should be closed. See also setpoint Neutral cont.