UTS6H and UPS questions

[Anonymous user]

I have a water pump connected to one of the circuits on my UTS6H and I use a Honda eu2000i for backup power. The generator has an eco throttle feature which adjusts the throttle according to the load. The generator can start the pump with eco throttle engaged if the pump is connected directly to the generator. However, when running through the UTS6H, the voltage drop due to the pump starting seems to be too much for the UTS6H to handle, and it cuts power to the pump circuit or cycles itself off and on. In both cases the pump fails to start. It seems the response time of the eco throttle is too slow to keep the voltage high enough for the UTS6H. If I disengage eco throttle (generator always on full throttle), the UTS6H works perfectly and the pump starts smoothly.

I discovered that if I have a UPS connected to the UTS6H, I can leave eco throttle engaged and the system stays on and the pump does start, but with a slight hesitation. Even though all the circuits have their source set to generator, the UTS6H seems to be smart enough to draw from the UPS to keep itself running. I'm happy with this solution but would like to find the optimal configuration that allows me to:

- use eco throttle
- avoid the hesitation when the pump starts
- minimize strain on all components.

So, I have the following questions:

- Would setting circuits 5 and 6 (or just one if only one is needed) to uninterruptible eliminate the hesitation I observed when the pump starts? In other words, would the UTS6H itself benefit from being powered from an uninterruptible circuit, or does it behave like that by default?
- Does the UTS6H need both circuits 5 and 6 to be powered to run, or can it run from just one? If so, which one? I would like to have the fewest number of uninterruptible circuits possible.

Thanks for your help!

[Anonymous user]

After giving it some thought and trying some things, I realize my questions could have been framed better:

- When utility power is off, does the UTS6H power itself from circuit 5 as it does when on utility power?

- If so, does the source setting for circuit 5 affect the way the UTS6H powers itself? In other words, does it switch its own power source according to the source settings for circuit 5 (i.e. generator, uninterruptible, etc.), or does it independently access Backup 1 and Backup 2 to maintain power to its control circuitry?

- If a circuit source is set to "generator" and the voltage drops, does the UTS6H cut off the circuit below a certain voltage, or does it pass along whatever voltage the generator is providing? If the circuit in question is circuit 5 (which powers the UTS6H itself) does it behave differently?

I observed that the UTS6H powers itself from circuit 5 when on utility power, but requires that circuit 6 be on as well, otherwise it gives an error message. For example, with only circuit 6 on, the UTS6H doesn't power up. With only circuit 5 on, it powers up but doesn't activate any of the circuits. If both are on and circuit 6 is turned off, after a few seconds an error message is displayed asking for the power to be cycled. If both are on and circuit 5 is turned off, the UTS6H shuts off. This leads me to conclude that it's powered via circuit 5 but it checks for circuit 6 before powering any circuits.

What's not clear is if it's powered via circuit 5 when utility power is off...

[BillP]

Hi,

On 3/15/2016 11:59 AM, Pablo said:

- When utility power is off, does the UTS6H power itself from circuit 5 as it does when on utility power?

Yes, the UTS6H requires circuit 5 to operate for safety purposes.

On 3/15/2016 11:59 AM, Pablo said:

- If so, does the source setting for circuit 5 affect the way the UTS6H powers itself? In other words, does it switch its own power source according to the source settings for circuit 5 (i.e. generator, uninterruptible, etc.), or does it independently access Backup 1 and Backup 2 to maintain power to its control circuitry?

When operating on generator, the Circuit will adjust it's output source to what ever the user has pre-assigned.

On 3/15/2016 11:59 AM, Pablo said:

- If a circuit source is set to "generator" and the voltage drops, does the UTS6H cut off the circuit below a certain voltage, or does it pass along whatever voltage the generator is providing? If the circuit in question is circuit 5 (which powers the UTS6H itself) does it behave differently?

The devices operating range is 84 - 142vac and will remove power to the circit unless specified as Uninterruptible, at which time the connected UPS will continue to power the circuit. The Voltage Sensitivity setting can help during slight power fluctuations. This can shorten the transfer time of the mechanical relays to help accommodate more sensitive loads. 

On 3/15/2016 11:59 AM, Pablo said:

I observed that the UTS6H powers itself from circuit 5 when on utility power, but requires that circuit 6 be on as well, otherwise it gives an error message. For example, with only circuit 6 on, the UTS6H doesn't power up. With only circuit 5 on, it powers up but doesn't activate any of the circuits. If both are on and circuit 6 is turned off, after a few seconds an error message is displayed asking for the power to be cycled. If both are on and circuit 5 is turned off, the UTS6H shuts off. This leads me to conclude that it's powered via circuit 5 but it checks for circuit 6 before powering any circuits.

What's not clear is if it's powered via circuit 5 when utility power is off...

Circuit 5 is the primary circuit for the UTS6H, even though all six circuits share the same electrical point. This is mainly because one circuit is required to provide a CPLD, which is a mechanical power disconnect. The purpose of the CPLD is to eliminate the possibility of back feeding power through the service panel onto the Service Electrical Wire exterior to the house and potentially causing damage or electrical shock to a lineman working on the power lines.

[wayne_i_apc]

Let me begin by saying that my knowledge of UTS operation is based on my investigation of a UTS10BI manufactured in 2008, so if there have been any significant design changes what I am explaining may be different from newer units...

The UTS is an "intelligent" automatic transfer switch. Under "normal" conditions the UTS will pass utility power from it's individual utility source inputs (INPUTS 1-10 for a UTS10x, or 1-6 for a UTS6x) directly to their respective OUTPUTS. It uses INPUTS 9 and 10 (5 and 6) to monitor the presence and quality of both phases of the utility power AND to power the UTS control circuitry when utility power is within acceptable limits.

On 3/15/2016 11:59 AM, Pablo said:

- When utility power is off, does the UTS6H power itself from circuit 5 as it does when on utility power?

Short answer-- no.

On 3/15/2016 11:59 AM, Pablo said:

- If so, does the source setting for circuit 5 affect the way the UTS6H powers itself? In other words, does it switch its own power source according to the source settings for circuit 5 (i.e. generator, uninterruptible, etc.), or does it independently access Backup 1 and Backup 2 to maintain power to its control circuitry?

The source setting for circuit 5 doesn't matter, the UTS automatically selects it's control circuitry power source.

When utility power is out of acceptable limits or missing, the UTS will AUTOMATICALLY change the power source for it's control circuitry to an available "good" (within acceptable voltage limits) backup source, either "GENERATOR" (backup 1) or "UPS" (backup 2). There are NO user options to select the control circuitry power source. Now, under a "backup" condition, the advanced features of the UTS (active load management, backup source overload protection, time delay features) become active, and user assigned output settings are activated, disconnecting the UTS outputs from their individual utility inputs and connecting them to the user assigned backup source (or none). The UTS will continue to monitor INPUTS 9 and 10 (5 and 6) for the return of "good" utility power in order to automatically return from a "backup" to "normal" condition.

The connection of the outputs to their assigned source is delayed about 10 seconds after the detection of "good" power from the source.

An output with it's source set to "UNINTERRUPTABLE" will be connected to the UPS inlet on the front of the UTS immediately when the setting is made, and persists regardless of the condition, good or bad, of utility and generator power.

On 3/15/2016 11:59 AM, Pablo said:

- If a circuit source is set to "generator" and the voltage drops, does the UTS6H cut off the circuit below a certain voltage, or does it pass along whatever voltage the generator is providing? If the circuit in question is circuit 5 (which powers the UTS6H itself) does it behave differently?

If ANY source deviates from acceptable voltage limits the UTS will disconnect that source from ALL outputs until the source returns to a "good" condition. As before, the UTS will automatically select ANY "good" source to power it's control circuitry, but if there are no sources providing "good" power to the UTS it will shut down.

On 3/15/2016 11:59 AM, Pablo said:

I observed that the UTS6H powers itself from circuit 5 when on utility power, but requires that circuit 6 be on as well, otherwise it gives an error message. For example, with only circuit 6 on, the UTS6H doesn't power up. With only circuit 5 on, it powers up but doesn't activate any of the circuits. If both are on and circuit 6 is turned off, after a few seconds an error message is displayed asking for the power to be cycled. If both are on and circuit 5 is turned off, the UTS6H shuts off. This leads me to conclude that it's powered via circuit 5 but it checks for circuit 6 before powering any circuits.

On page 10 of the Site Preparation and Installation Guide a "NOTE" states that 240 volts must be present across circuits 9 and 10 (5 and 6). This permits the UTS to monitor both phases of the utility power, and assumes that if either phase deviates from acceptable voltage limits that there is a problem with utility source, and a return from backup should not take place. The individual loss of power to either INPUT 9 (5) or 10 (6) would be a highly unusual situation, likely requiring "special" attention!

Regarding your issue starting your well pump, what is the horsepower rating of the pump, and how long in the "hesitation" when it is connected to the UTS? I am going to guess that the hesitation is due to the UTS briefly disconnecting the generator while it is below acceptable voltage until the eco-throttle lets the generator "spool-up" enough to deliver the power needed to start the pump.

I hope this explanation helps you understand how your UTS behaves!

[Anonymous user · Accepted solution]

Wayne, thank you for taking the time to post a detailed response. You explanations match what I suspected and later observed.

I do have to clarify one thing: the UTS6H is a 120v-only unit, so your notes on circuits 5 and 6 are not quite right for this particular model. It does in fact use 5 and 6 to monitor both phases, but it only requires circuit 5 to power up. There is no need for 240v to be present across 5 and 6 with this particular model. Of course, if circuit 6 is turned off, after a few seconds it will throw an error message and cut power to all circuits (your utility has lost 1 leg! Not good!), but the panel remains on. Interestingly, it doesn't seem to be able to tell if 5 and 6 are actually on different phases. I mistakenly put 5 and 6 on the same leg at one point and the panel worked without trouble. It seems to assume that the installation is correct.

To answer the question about the pump: It's a 1/2 hp pump. The panel shows it using 975 W and 10 A when running, which is handled easily by my Honda eu2000i generator. Before I connected a UPS, the startup surge was causing the voltage to drop too much when eco-throttle was engaged, and the UTS6H would shut down briefly while the generator caught up. It only takes a second or less for the generator to catch up, but it was enough to cause the panel to turn power off to the pump circuit, and then shut itself off for a few seconds, the result being that the pump wouldn't turn on. When the UPS is connected, the panel can stay on, which means that, during pump startup, if it turns power off to the pump, it will be available to turn the power back on a fraction of a second later when the generator catches up. This brief interruption leads to the hesitation I observed when the pump starts up, but the pump doesn't seem to mind. It's a very simple device! Also, the hesitation doesn't always happen, and I think that's dependent on the other loads present when the pump turns on and how the UTS6H handles the load shedding.

In short: a backup system with a eu2000i, a 1/2 hp pump, and a UTS6H will work provided there is also a UPS and you don't mind the possibility of other circuits being shed when the water pump kicks in.