How does "split phase" 240VAC wiring work in UPS, Switched PDU and ATS?

[MisterPic]

Hi!

I am not familiar with "split phase" 240VAC wirings - when we have L1 L2 and Gnd as the utility power source.

And i am trying to understand how this type of power system is design in APC products such as UPS, Switched PDU and ATS:

1) UPS – SRT5KXLT-5KTF

https://download.schneider-electric.com/files?p_Doc_Ref=SPD_SCUA-9XKGYW_EN&p_enDocType=Technical+Dra...

   a) what we have at the output NEMA L60-30R which is on the UPS unit: L1+L2+Gnd? Or L1+N+Gnd?

And we have on the same output when UPS is in bypass?

   b)  what we have at the output NEMA L60-20R which is on the TRANSFORMER unit: L1+L2+Gnd? Or L1+N+Gnd?

And we have on the same output when UPS is in bypass?

   c) Do we always have L+N+Gnd at the 5-20R output on the TRANSFORMER unit ?

2) Switched PDU – all PDU with L60-20P or L60-30P – for example APDU9941 https://download.schneider-electric.com/files?p_Doc_Ref=APDU9941_EN&p_enDocType=Technical+Drawing&p_...

The wiring diagram shows that one pin of each power outlet is connected via controlled relay and the second one is always connected to “neutral” common bus.

But when we are talking about L60 sockets – there is L1, L2 and Gnd, no Neutral.

Does it means that even when power socket is off – we still have 120VAC between “Neutral” and Gnd at this socket?

So, how does it work when we connect to APS UPS (L1+N?) or just to utility power source (L1+L2)?

3) ATS units

https://download.schneider-electric.com/files?p_Doc_Ref=AP4431A_EN&p_enDocType=Technical+Drawing&p_F...

There is the same question as for Switched PDU – according with wiring diagram – there is Line and Neutral, not Hot line 1 and Hot line2. Is it ok for ATS unit to have both input options to work properly?

That means that there is no internal components difference with Euro ATS options?

[ryan1969]

Hello, @MisterPic 

Understanding “split phase” 240VAC wiring in UPS, Switched PDU, and ATS can be quite technical, but I’ll do my best to explain it clearly.

UPS – SRT5KXLT-5KTF: a) The output NEMA L6-30R on the UPS unit typically provides L1+L2+Gnd. This means you have two hot lines (L1 and L2) and a ground (Gnd), with no neutral. When the UPS is in bypass mode, the output should remain the same as it simply passes through the utility power without conditioning.

b) For the output NEMA L6-20R on the TRANSFORMER unit, it’s likely to be L1+L2+Gnd as well, similar to the L6-30R output. The transformer’s role is to step down or step up the voltage, not to change the phase configuration. c) The 5-20R output on the TRANSFORMER unit typically provides L+N+Gnd, where L is one of the hot lines (either L1 or L2), N is neutral, and Gnd is ground. This is because the 5-20R is a standard 120V outlet.

witched PDU: For PDUs with L6-20P or L6-30P, the “neutral” common bus is actually connected to one of the hot lines (either L1 or L2) because these are 240V outlets without a neutral. When the power socket is off, there should not be 120VAC between “Neutral” and Gnd because there is no neutral; instead, there is a potential of 120VAC between each hot line and ground when measured separately.

ATS units: ATS units can be designed to work with both L1+L2+Gnd and L1+N+Gnd configurations. The internal components are capable of handling either input option. The difference between Euro ATS and others is usually the voltage levels and frequency, but the basic functionality remains the same. They switch between two power sources to provide a continuous power supply.

I hope my suggestion is helpful for you.