jar546
CBO
If you are not in the 2017 NEC yet, here is a change coming for when you get there that is a biggie:
Added to the text of 700.10(D)(3) is the following sentence:
The integrity of the generator control wiring shall be continuously monitored. Loss of integrity of the remote start circuit(s) shall initiate visual and audible annunciation of the generator malfunction at the generator local and remote annunciator(s) and start the generator(s).
Compliance with the new requirement thus requires three elements:
1. Continuous monitoring of generator signaling circuits
2. Visual and audible annunciation of changes in state
3. Automatic transmission of an engine start signal and alarm when a problem is detected
Under normal circumstances the ATS uses an NC (normally closed) contactor that when energized in normal operation is open. When there is a loss of power, the contactor closes (normal position) therefore sending the signal to the generator to start. This can be a problem if the wires that connect are broken and open or shorted. Either way, it can cause a loss of signal to the generator and it will not start.
Some think you can simply add another wire to a normally open contactor creating a 3 wire system but this is not a failsafe approach and although helpful, does not cover all shorts and opens on the 2 circuits and more importantly, does not monitor and send a signal to the annunciator that there is a problem.
I looked into solutions from the generator control industry and found that ASCO makes modules, one for the ATS and one for the Generator that monitors the start circuit wiring and sends a signal to start the generator with either a problem with an open or short. In addition it sends the appropriate signal for visual and audio to the annunciator panel(s).
The start circuit monitoring devices can be installed new or for a retrofit. As a plans examiner, I believe we would have to require this or a similar compliant system even for an ATS replacement. Since we are talking about emergency systems that are critical such as healthcare, I believe it is our duty to ensure compliance even during component swap outs. Thoughts?
Added to the text of 700.10(D)(3) is the following sentence:
The integrity of the generator control wiring shall be continuously monitored. Loss of integrity of the remote start circuit(s) shall initiate visual and audible annunciation of the generator malfunction at the generator local and remote annunciator(s) and start the generator(s).
Compliance with the new requirement thus requires three elements:
1. Continuous monitoring of generator signaling circuits
2. Visual and audible annunciation of changes in state
3. Automatic transmission of an engine start signal and alarm when a problem is detected
Under normal circumstances the ATS uses an NC (normally closed) contactor that when energized in normal operation is open. When there is a loss of power, the contactor closes (normal position) therefore sending the signal to the generator to start. This can be a problem if the wires that connect are broken and open or shorted. Either way, it can cause a loss of signal to the generator and it will not start.
Some think you can simply add another wire to a normally open contactor creating a 3 wire system but this is not a failsafe approach and although helpful, does not cover all shorts and opens on the 2 circuits and more importantly, does not monitor and send a signal to the annunciator that there is a problem.
I looked into solutions from the generator control industry and found that ASCO makes modules, one for the ATS and one for the Generator that monitors the start circuit wiring and sends a signal to start the generator with either a problem with an open or short. In addition it sends the appropriate signal for visual and audio to the annunciator panel(s).
The start circuit monitoring devices can be installed new or for a retrofit. As a plans examiner, I believe we would have to require this or a similar compliant system even for an ATS replacement. Since we are talking about emergency systems that are critical such as healthcare, I believe it is our duty to ensure compliance even during component swap outs. Thoughts?