Parallel operation of Emergency generator with Main/Essential Generator

[NickParker]

Does ABS/SOLAS prevent the parallel operation of emergency generator with Main/essential generators?
The intention is to test the emergency generator by running it in parallel with the essential generator and for the purpose of bumpless transfer when the essential power is reinstated.

 

[waross]

A concern would be the overloading of the emergency generator should the main source fail while paralleled.
The proper operation of your emergency transfer circuits may be inhibited with the emergency generator in parallel.
Testing while underway may not be a good idea.
Testing while tied alongside may be acceptable.
Of course you need sync check to parallel.
There is one design of transfer switch that gives an open transition so fast as to be bumpless.
These switches need a synch check relay.
They sometimes take minutes to drift into synchronization before a safe transfer is made.
You would need an added contactor.
Disabling the mechanical interlock protection on the existing transfer switch is a really bad idea.

 

[TugboatEng]

Can you put all of your loads on the main bus, put your emergency generator on the unloaded emergency bus, and then apply loads to the e-bus until you reach your desired test load without disruption to the plant?

 

[NickParker]

A concern would be the overloading of the emergency generator should the main source fail while paralleled.
The proper operation of your emergency transfer circuits may be inhibited with the emergency generator in parallel.
Testing while underway may not be a good idea.
Testing while tied alongside may be acceptable.
Of course you need sync check to parallel.
There is one design of transfer switch that gives an open transition so fast as to be bumpless.
These switches need a synch check relay.
They sometimes take minutes to drift into synchronization before a safe transfer is made.
You would need an added contactor.
Disabling the mechanical interlock protection on the existing transfer switch is a really bad idea.

Also, the emergency generator may be used to start the auxiliaries of the main engine/propulsion when the main power fails. We have breaker on both the sides, no ATS

 

[NickParker]

Can you put all of your loads on the main bus, put your emergency generator on the unloaded emergency bus, and then apply loads to the e-bus until you reach your desired test load without disruption to the plant?

1. Run the e-bus from the supply via main switchboard
2. Start the emergency generator
3. Run the emergency generator without closing the emergency generator main circuit breaker at the emergency switchboard
4. close the emergency generator main circuit breaker
5. Gradually increase the speed of the emergency generator to apply the loads.

Is this what you are suggesting?

 

[TugboatEng]

Transfer all loads that are on the E-Bus to the main bus, open e-bus tie breaker, start EDG, close EDG breaker to E-bus, transfer available loads from the main bus to the E-bus until the desired load is achieved. Reverse steps to return to normal operation.