Issue:What is the function of the AMS switch, and how should it be installed and tested, and how can you troubleshoot it if it doesn't work properly
Product Line:Circuit Breakers
Resolution:The AMS solution has been superceded by the ERMS solution. The following information pertains to the old AMS system.
Purpose:
The AMS switch temporarily eliminates the short-time delay setting of the circuit breaker and provides a circuit protection system with two modes: a normal mode and a maintenance mode (in which potential arc flash energy is reduced).
In normal mode, the upstream circuit breaker acts in accordance with the settings provided in the electronic trip unit that provides selective coordination of the electrical distribution system.
In maintenance mode, the upstream circuit breaker disregards the preset time-delay and operates to clear the fault condition with no intentional short-time delay. In this mode, the upstream circuit breaker responds as a ZSI circuit breaker that fails to receive a restraint signal, as described previously. By responding quickly to an arcing fault, incident energy is reduced. However, selective coordination is not preserved when the AMS is in maintenance mode.
Installation:
The AMS switch is designed to be factory installed in Switchboard and Switchgear. It could also have been installed in the field but it required a breaker with an A, P, or H trip unit and purchase of the following:
- Restraint Interface Module (RIM), catalog number S48890 (120 Vac/24 Vdc) or S48895 (240 Vac/24 Vdc).
- Kit 84957 (label and components for required switches; includes the following
-Instruction Bulletin NHA40218
-AMS nameplate (80298-173-01)
-AMS danger label (NHA41456)
-C&KJ AMS push button (KM3301RR05Q) (button used for testing) - The following parts were ordered separately:
-RIM (S48890)
-Switch with blue indicator light (9001K11J38LLL)
-Switch contact block (9001KA3)
-Padlock attachment (9001K7)
-Remote Pilot Light (the bulletin shows 9001KP1L9 or 9001KP35L9 but they use whatever they want)
See attachment for installation instructions.
Testing:
See attached bulletin for testing instructions.
Troubleshooting:
Ensure wiring is correct and all components are functioning properly.
Related documentation:
• Reducing Fault Stress with Zone-Selective Interlocking (Document No.
0600DB0001)
• Guide to Power System Selective Coordination 600 V and Below (Document No.
0100DB0603)
• Alternate Maintenance Setting (AMS) Switch Handout (Document No.
8998HO1001)
• Arc Flash Reduction Systems—Are They Always a Good Idea? (Document No.
0600DB0901)
