Why does galaxy 3500 goes into internalbypass mode when three phase supply is lost?

[aelma93]

Current have 7 galaxy 3500 10KVA installed as backup supply for 7 substation.

The UPSs are installed in a dual supply manner, 3 phase supply and single phase bypass supply. 

We currently have a 2 monthly load test on the UPS, where the load test is completed by turning off the 3 phase supply to the UPS, whilst single phase supply is available. This is to simulate a power loss, whilst also keeping the single phase available for internalbypass incase any issues with the UPS. 

The following was noted:

• some UPS goes into battery mode (as expected)
• whilst some UPS goes into bypass mode

why is this?, is this a configuration issue?, where can I get full configuration manual. The current available installation and operation manuals dont have anything regarding this.

[KarimEissa · Accepted solution]

Hello,

In order to investigate this issue,you can provide a picture of  the raw status data from display to verify if there a hardware issue appeared in the unit power module,since your are performing load bank test,it might the UPS in  Bypass due to fault, Over load

UPS in Bypass due to fault, may be found during over loads. Check for over loads on the UPS, check for balanced loading across all three phases. Check application the UPS is being used in such as to support motor loads, printers or other equipment that may draw an inrush current.

Often times if motor type loads are being used you can get High DC events and transfers to bypass or load dumps as a result. The UPS is not really rated for motor type loads as the UPS inverter is rated for kVA, not kW. Other words the UPS is not fully rated output and the inrush that is characteristic of motor loads can cause over load of the inverter.

If the SUVT gets an high inrush current on the output and bypass voltage is available it will swap to bypass operation using the internal Static bypass switch (SCR's). 

If load is dropped and cause of output over error is not associated with a Low DC battery event, over load or High DC event then replace the Power Module, otherwise it is a normal system behaviors during overloads to turn on static bypass operation 

Regards,

Karim