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Emergency Power Supply System (EPSS) Reports Show Multiple Generator Starts And Stops

Goals and Symptoms
 
Symptoms:
When an EPSS report is showing multiple starts and stops for a generator, there is a good chance the debounce settings need to be changed. Here is an example of a report where this is happening:

Taking a look at generator #1 (the yellow bars), the report shows that the generator started at 12:58:13.103 and stopped at 12:58:13.157, only a 54 millisecond difference. The same is happening in generator #2 (the green bars), a 56 millisecond difference.
 
Causes and Fixes

Cause:
CM4000 meters with firmware versions of 14.400 or older had a maximum debounce time of 50ms, and the only options were 5ms and 50ms (newer firmwares allowed more options). In the above example, when the difference in time between the starting and stopping of the generator is more than 50 milliseconds, this issue can be corrected by editing the debounce register. The debounce setting is actually a measurement of the vibration caused by the relay tripping. This vibration is supposed to dissipate within a few milliseconds, but sometimes takes longer.

The default setting for the debounce register is 5 milliseconds, but this can be reconfigured to as high as 200ms in 5ms increments depending on the currently installed firmware version.

Resolution:
In some cases, like the one illustrated above, the chosen debounce time may not be high enough for the vibration to dissipate, so try a higher value if needed (200ms maximum).

Note: The procedure to change the debounce time will be different based on what your meter firmware is.

A register write is required to change the debounce setting. In the illustrated example, the customer has an IOC44 in Slot B of the CM4000, and has the generator statuses wired to I/O Points 19, 20, 21, and 22. The debounce setting is held in the base I/O register +11. These are the register writes to change the debounce settings for this example configuration to 200ms:

If you have firmware version that is higher than 14.400, then you would use the following modified precedure to get a 200ms debounce time:

Register 8000 -> 9020 for command mode
Register 4851 -> 200 for debounce register for IO Point 19
Register 4881 -> 200 for debounce register for IO Point 20
Register 4911 -> 200 for debounce register for IO Point 21
Register 4941 -> 200 for debounce register for IO Point 22
Register 8001 -> 1 for saving changes
Register 8000 -> 9021 for closing command mode

Once the debounce setting is changed, it will ignore any vibrational signal that occurs in the first 200 milliseconds of the relay switching.

If you have firmware version 14.385 beta, then you would use the following modified precedure to get a 200ms debounce time:

Register 8000 -> 9020 for command mode
Register 4851 -> 1 for debounce register for IO Point 19
Register 4881 -> 1 for debounce register for IO Point 20
Register 4911 -> 1 for debounce register for IO Point 21
Register 4941 -> 1 for debounce register for IO Point 22
Register 8001 -> 1 for saving changes
Register 8000 -> 9021 for closing command mode

If you have firmware version 14.400 or less, excluding the 14.385 beta, then you would use the following precedure to get a 50ms debounce time (50ms is the maximum with these firmware versions):

Register 8000 -> 9020 for command mode
Register 4851 -> 1 for debounce register for IO Point 19
Register 4881 -> 1 for debounce register for IO Point 20
Register 4911 -> 1 for debounce register for IO Point 21
Register 4941 -> 1 for debounce register for IO Point 22
Register 8001 -> 1 for saving changes
Register 8000 -> 9021 for closing command mode

For a register list of the CM4000, please see this link:

Series 4000 Circuit Monitor (CM4/CM4000) Register List with 14.400 firmware functionality
http://download.powerlogic.schneider-electric.com/C1257C930050CCCB/All/257C3F004C0D47656E5F555300221544?Opendocument
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