Generator output breaker shunt trip
- Thread starter tloescher
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ron
Senior Member
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- New York, 40.7514,-73.9925
Re: Generator output breaker shunt trip
What type of alarms activate the shunt trip? It is emergency power off buttons, or operation alarms like high water temp, oil, frequency, etc?
Sometimes the shunt is to protect the generator, personnel or downstream equipment (GFI).
[ October 16, 2003, 04:24 PM: Message edited by: ron ]
What type of alarms activate the shunt trip? It is emergency power off buttons, or operation alarms like high water temp, oil, frequency, etc?
Sometimes the shunt is to protect the generator, personnel or downstream equipment (GFI).
[ October 16, 2003, 04:24 PM: Message edited by: ron ]
Re: Generator output breaker shunt trip
Are you perhaps referring to the "panic switch" required for data equipment rooms? 645.10 requires a means (shunt trip? or knife switch?) to disconnect power to all electronic equipment and the HVAC equipment and to cause all fire dampers to close. Usually these are found as a red mushroom switch near to the exit door. By hitting this switch, all power to the IT room is shut off via relays or shunts. A shunt trip on the emergency generator would not be required if the transfer switch was located appropriately.
A generator supplying power exclusively for data processing is not legally an "emergency" generator, but rather an optional standby generator. There is no life safety if the power is lost. See article 702.
Are you perhaps referring to the "panic switch" required for data equipment rooms? 645.10 requires a means (shunt trip? or knife switch?) to disconnect power to all electronic equipment and the HVAC equipment and to cause all fire dampers to close. Usually these are found as a red mushroom switch near to the exit door. By hitting this switch, all power to the IT room is shut off via relays or shunts. A shunt trip on the emergency generator would not be required if the transfer switch was located appropriately.
A generator supplying power exclusively for data processing is not legally an "emergency" generator, but rather an optional standby generator. There is no life safety if the power is lost. See article 702.
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Re: Generator output breaker shunt trip
Most leave shunt trips active for generator self protection. You might as well shut down when you have low oil, so you could add oil, then restart. If you didn't shut down on this type of alarm, the engine might be permanently damaged, and you will not restart.
The best plan to help with this reliability problem, is having a "+1" generator.
[ October 16, 2003, 04:45 PM: Message edited by: ron ]
Most leave shunt trips active for generator self protection. You might as well shut down when you have low oil, so you could add oil, then restart. If you didn't shut down on this type of alarm, the engine might be permanently damaged, and you will not restart.
The best plan to help with this reliability problem, is having a "+1" generator.
[ October 16, 2003, 04:45 PM: Message edited by: ron ]
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Re: Generator output breaker shunt trip
I would advise caution in the use of language here. If you are providing back-up power for a data center, and if the reason you are doing this is related to business and profit and serving your customers, then the word ?emergency? does not apply. In the context of electrical codes, that word is related to the protection of life and limb. It may be appropriate to run an ailing generator to the point of its own destruction, if that action helps people get out of an unsafe building. It is not appropriate to allow a generator to self destruct, if that action is only done to protect information.
Your installation would fall under 702, ?Optional Standby Systems,? and not under 700, ?Emergency Systems,? or 701, ?Legally Required Standby Systems.? But that is as far as I can take an answer. I do not know where in the code you can find a statement that permits the disabling of a safety shutdown feature.
I would advise caution in the use of language here. If you are providing back-up power for a data center, and if the reason you are doing this is related to business and profit and serving your customers, then the word ?emergency? does not apply. In the context of electrical codes, that word is related to the protection of life and limb. It may be appropriate to run an ailing generator to the point of its own destruction, if that action helps people get out of an unsafe building. It is not appropriate to allow a generator to self destruct, if that action is only done to protect information.
Your installation would fall under 702, ?Optional Standby Systems,? and not under 700, ?Emergency Systems,? or 701, ?Legally Required Standby Systems.? But that is as far as I can take an answer. I do not know where in the code you can find a statement that permits the disabling of a safety shutdown feature.
stevebrown
Member
Re: Generator output breaker shunt trip
NFPA 110, "Emergency and Standby Power Systems" is something you may want to review. This standard distinguishes between applications where failure of the generator could result in loss of human life or serious injuries (Level I) or applications less critical to human life and safety (Level II). I'd say you have a Level II application since you are primarily providing backup power to prevent financial loss, not human safety.
As a Level II application, the standard has a list of required safety indications and automatic shutdowns. You may want to look at this prior to disabling any shutdowns.
The generator vendor should be very familiar with this standard, and probably has a copy you can look at.
NFPA 110, "Emergency and Standby Power Systems" is something you may want to review. This standard distinguishes between applications where failure of the generator could result in loss of human life or serious injuries (Level I) or applications less critical to human life and safety (Level II). I'd say you have a Level II application since you are primarily providing backup power to prevent financial loss, not human safety.
As a Level II application, the standard has a list of required safety indications and automatic shutdowns. You may want to look at this prior to disabling any shutdowns.
The generator vendor should be very familiar with this standard, and probably has a copy you can look at.
brian john
Senior Member
- Location
- Leesburg, VA
Re: Generator output breaker shunt trip
I've work on a fair number of generators and can say the only time I have seen shut trip on the Genset CB is when it was part of a GFP system, or customer requested for shut down for a specific reason.
Engine controls will have built in engine shut down, if engine safety's are activated the unit will shut down and at that point who cares if the output CB is close cause your standing in the dark. If your responsible for the low oil or engine coolant, well get your resume in order.
I've work on a fair number of generators and can say the only time I have seen shut trip on the Genset CB is when it was part of a GFP system, or customer requested for shut down for a specific reason.
Engine controls will have built in engine shut down, if engine safety's are activated the unit will shut down and at that point who cares if the output CB is close cause your standing in the dark. If your responsible for the low oil or engine coolant, well get your resume in order.
brian john
Senior Member
- Location
- Leesburg, VA
Re: Generator output breaker shunt trip
One of our diesel tech's just told me I was wrong Onan has been shunt tripping the output CB for some time to minimize low voltage problems (he assumes) as the engine is shuting down from an engine problem.
One of our diesel tech's just told me I was wrong Onan has been shunt tripping the output CB for some time to minimize low voltage problems (he assumes) as the engine is shuting down from an engine problem.
pierre
Senior Member
- Location
- Westchester County, New York
Re: Generator output breaker shunt trip
I would say that the reason some disconnect the safety devices in this type of scenario is to protect against the cost of preventative maintenance program. Suggest to them a preventative maintenance program and keep the shunt trip active. Everyone but the accountant will be happy
Pierre
[ October 18, 2003, 02:13 PM: Message edited by: pierre ]
I would say that the reason some disconnect the safety devices in this type of scenario is to protect against the cost of preventative maintenance program. Suggest to them a preventative maintenance program and keep the shunt trip active. Everyone but the accountant will be happy
Pierre
[ October 18, 2003, 02:13 PM: Message edited by: pierre ]
Re: Generator output breaker shunt trip
The shunt trip feature is usually connected to CT's measuring for reverse power. In otherwords they keep the generator from becoming a motor.
This is when the generator is serving as a peaking power plant, in parallel with other generators.
The shunt trip feature is usually connected to CT's measuring for reverse power. In otherwords they keep the generator from becoming a motor.
This is when the generator is serving as a peaking power plant, in parallel with other generators.
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