Failed to perform total power off to Symmetra PX 96/160kw

[BillP]

This question was originally posted by sataa on APC forums on 9/9/2018

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I have Symmetra PX 96/160kw that have faulty, the client team change operation mode to maintenance bypass, i.e. total load on utility power.

I receive the alarm  Local Management to UPS lost, the LCD display failed to communicate with the UPS but still can read the lines voltages. 

I have changed the network cards, the intelligent module, the power supply, the communication cables... still no change

I tried to perform a total power off by :

• • Set the UPS SYSTEM ENABLE switch to the OFF position              
  • Set the Q2 switch to the OFF position. 
  • Set the Q1 switch to the OFF position. 
  • Set the Q5 breaker to the OFF position.              
  • Set maintenance bypass switch (Q3) to OFF position.   
  • Set Subfeed breaker to OFF position.   
  • Set the DC DISCONNECT switch to the OFF position on   the PDU with modular batteries              
  • Disconnect all battery units by pulling them out to the red disconnect line          
  • Pull all the power modules out of the cabinet. 
  • Pull out the static bypass module.

unfortunately, the failure to do that and the network card and the LCD display continues to have power and working.

anybody can clarify this issue for me? with thanks.

[voidstar_apc]

This was originally posted on APC forums on 9/10/2018

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The card and display are powered by the modular distribution panel at the output of the UPS. That's also what measures the line voltages. Since the UPS is in bypass, the card and display are still powered.

[BillP]

This reply was originally posted by sataa on APC forums on 9/10/2018

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Thank you voidstar for information, do you have an SLD showing how LCD display and network card is connected.

[voidstar_apc · Accepted solution]

This was originally posted on APC forums on 9/10/2018

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I suggest contacting three-phase support for more details:

http://www.apc.com/us/en/support/contact-us/

From what I remember, the modular distribution panel has its own power supply (powered by the UPS output) that runs the metering boards (these measure currents through the modular breakers and subfeeds) as well as running the network card and display. With the UPS off you can still manage the distribution panel.