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UPS: Bypass not in range ; distorted waveform and SNMP shutdown signal

APC UPS Data Center & Enterprise Solutions Forum

Schneider Electric support forum for our Data Center and Business Power UPS, UPS Accessories, Software, Services, and associated commercial products designed to share knowledge, installation, and configuration.


UPS: Bypass not in range ; distorted waveform and SNMP shutdown signal


I did have some problem with the shutdown signal from NMC3 and servers.

My servers are getting power from SRT5KXLI with built in NMC3. They are configured to wait until low battery before safe shutdown.

A couple of days ago, UPS detected "UPS: Bypass not in range ; distorted waveform" and UPS started feeding the devices from the battery due to this.

However, my servers went immediately to the safe shutdown without waiting for "low battery". Later on when I tried to reproduce the issue by cutting the input power of the UPS, servers were still on as should be since UPS battery was full.

I would like to ask when UPS detects distorted waveform, does it send shutdown signal through SNMP?

Furthermore, how can I simulate a distorted waveform so that I can debug this issue?

Some details:

Green mode is disabled and UPS is on online mode.

Network firmware: v1.5.1.1

Model number: 0N-1557

Hardware Revision: 3

Thanks in advance

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1 Reply 1

Re: UPS: Bypass not in range ; distorted waveform and SNMP shutdown signal

Hi Laxarus,


Do you have a the loading for the UPS as well as the expected runtime?

You should look at the event to to see when the event occurred and then go to the data log to see what the readings were around the time of the event. The default data log interval is normally 10min and we reduce that down to 1 min or 60 sec (the lowest interval). Normally the only time the unit goes onto battery during such an event is if set thresholds were exceeded.


You should see if the data log shows what the battery charge % dropped to since the shutdown command will only be sent if the % reaches the 4 min +1 min mark in your case.


You would not be able to reproduce the distorted wave form without specific switching equipment for the UPS input under controlled conditions. If you had a large HVAC system you can try turning that on/off to see if the system can reproduce the distortion. Would only look at these options if this was a constant issue.


The main points you can look at is the amount of load on site and the runtime predicted by your system. In our experience there is very little you can do about distortion on the input.

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