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UTS10BI "other" source input option and circuit 9-10 power?

Discussion in Universal Transfer Switch started by N , 7/13/2015 7:05 PM
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UTS10BI "other" source input option and circuit 9-10 power?

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  • HI the manual says there is another option to use "other" source besides grid or generator, however the manual goes into no further detail.  I would like to have, grid, solar and generator functions.  Is this possible?   ALso it says circuits 9 and 10 must be powered to work?  What if the power fails on circuit 9-10 how does the unit work without power on these circuits?  Can I use solar as the Other source?



  • N,

    Circuits 9 and 10 are required to be powered on as they power the logic of the unit.  As far as an "other" source please see the quote below from page one of the product manual:


    "The APC by Schneider Electric Universal Transfer Switch (UTS) is a fully automatic transfer switch for use in optional standby systems in homes or small businesses. This unit provides safe, convenient power for up to ten circuits in the home or office. Power is derived from one or two independent backup sources. Backup sources being a generator, an uninterruptible power supply (UPS), a solar inverter, or another alternative energy source."

    The bolded may lead someone to believe they can connect the UTS to grid power, a solar inverter, and a generator, (because one would not consider the grid as a source of back up power) however you may only connect two sources of power.  There is a small outlet to connect a Back-UPS APC UPS that you could use for a small generator, but it is limiting as a 3rd source of power and not meant for solar or grid.


  • Hi Norm,

    EDIT: On my UTS running V2 firmware the circuit source does NOT fallback to utility power when the power is lost at BACKUP SOURCE 2 if the CIRCUIT SOURCE is set to "UNINTERRUPTABLE". Any other CIRCUIT SOURCE setting provides ONLY utility power when it is available.

    Before you get too concerned about the "other source" designation, remember that the primary function of a transfer switch is to TRANSFER the input source from the "main" source (utility power through the house main panel) to a "backup" source. While the UTS WILL allow you to individually select BACKUP SOURCE 2 for outputs 2 through 8 when there is "good" utility power (CIRCUIT SOURCE is set to "UNINTERRUPTABLE", assuming the role of a UPS), the total load to that backup source is limited to 15 amps at 120 volts. Assuming your solar system provides 120 volts at 60 Hz, <I THINK> you could substitute it for a UPS in this arrangement, such that when there is "good" power provided by the sun, it would be selected, and (otherwise the UTS would fallback to utility, NOW CONFIRMED NOT TRUE)... Another member recently mentioned his desire to use the UTS "off grid", maybe he will contribute his thoughts. While this may not be what APC had in mind when they designed the UTS, it seems like a reasonable approach. This MAY inspire lots of debate!

    There has been a lot of confusion about the need for power on circuits 9 & 10 for the UTS10BI to operate. For the UTS to provide all it's functions under "normal" utility conditions you must have 240 volts applied to INPUT circuits 9 & 10. There are also the TWO backup source inputs that will allow the UTS to operate under REDUCED CAPACITY when only they are providing power. The "primary" backup source (BACKUP SOURCE 1) is a 240 volt input, usually connected to a generator. When this input is "hard wired" the UTS may support 50 amps per PHASE max or 20 amp per circuit. The "secondary" backup source (BACKUP SOURCE 2) is a 120 volt front panel IEC input and is expected to be connected to a UPS, and is limited to 15 amps max. If power is applied to ONLY ONE of these inputs, the UTS will provide all it's features within the capacity of the respective input.

    In other words, when on UTILITY power, with ALL 10 input circuits connected and powered from the home's main circuit breaker panel, the UTS will pass UTILITY power to the 10 output circuits transparently (like there was no transfer switch at all). It will provide power quality monitoring, power usage monitoring and reporting on a circuit-by-circuit basis, and overcurrent monitoring and protection. If no other power is connected to either "backup" source, then (obviously) everything will shutdown if utility power is lost. If utility power is lost to only circuits 9 & 10 (main panel breaker connected to circuits 9 &10 turned off or tripped), the UTS will "go dark" but utility power will still pass to the remaining circuits 1 through 8.

    If a 120 volt source (say a UPS) is connected to and powering "BACKUP SOURCE 2" to the UTS through the front panel IEC input at the same time there is "good" utiity power, the UTS pass the UPS power to user selected ("UNINTERRUPTABLE") 120 volt outputs at all times and utility power to all others. If utility power is lost to circuits 9 & 10, the UTS will continue to operate on the UPS, and provide 120 volt power to circuits 2 through 8 (with a brief switch-over delay on non "UNINTERRUPTABLE" selected circuits), providing all it's automatic functions now including load managment to prevent overloading the UPS. Note that circuit 1 is the source for the front panel convienence receptical that is assumed to be the input to the UPS, so under these conditions, circuit 1 is NOT powered.

    If a 240 volt source (say a generator) is connected to and powering "BACKUP SOURCE 1" to the UTS at the same time there is "good" utility power ONLY the utility power will pass to the UTS outputs (except for the UPS selections described above). If utility power is lost to circuits 9 & 10, the UTS will continue to operate on the generator, and provide power to all 10 circuits (with a brief switch-over delay on non "UNINTERRUPTABLE" selected circuits), providing all it's automatic functions now including load managment to prevent overloading the generator.

    Finally, if any backup source is NOT powered when utility power fails, the UTS will resume operation and user programable circuit settings stored in non-volatile memory will be applied when the respective backup source comes online.

    Let the discussion begin!


  • Wow, good job Wayne for explaining the operation in detail.  This is the plan, solar power will be connected to the GRID input and Grid will be connected to the BACKUP 1.  When my solar system requires maintenance, I need to shut it down, and the house could go back on grid.  The solar system from Schneider of course XW6848+NA will provide enough power to run the 10 circuits I have planned.  If I feel the solar can't keep up then I will program the individual circuits back to BACKUP 1 (grid in my case).  I will wire a  240volt contactor to run my AC where circuits 9+10 would connect, because this circuit is not designed to hold such a load, DO you see  any issues with this set up?



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