Redoak 3046 Show full post »
grsthegreat
This does not make any sense. The generator isn't producing dirty power. Ive installed many of the soft starters on heat pumps and all have fired up. Assuming that there is enough overall available power that is. Now if your running near max load against generator when heat pump is called for, then i can see an issue.
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78buckshot
I can offer my view based on experience on my own system and at least two of our customers systems. I have a 4 zone control panel for my HVAC, conventional A/C and single stage furnace, the zone panel electronics do not like generator power but I can wire around the panel and run the condensing unit and furnace without issues, I do not have a soft start module. Similar problems in two different locations with customers equipment, on these I installed a double conversion UPS just to handle the 24vac control supply for the zone panel-these systems are working without any other modifications. Just my 2 cents.
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Redoak 3046
grsthegreat;n59780 wrote:
This does not make any sense. The generator isn't producing dirty power. Ive installed many of the soft starters on heat pumps and all have fired up. Assuming that there is enough overall available power that is. Now if your running near max load against generator when heat pump is called for, then i can see an issue.


There was very little load on the generator when we were trying to get AC to run. Even with some load, it will run as long as the lock out is bypassed.
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Redoak 3046
78buckshot;n59783 wrote:
I can offer my view based on experience on my own system and at least two of our customers systems. I have a 4 zone control panel for my HVAC, conventional A/C and single stage furnace, the zone panel electronics do not like generator power but I can wire around the panel and run the condensing unit and furnace without issues, I do not have a soft start module. Similar problems in two different locations with customers equipment, on these I installed a double conversion UPS just to handle the 24vac control supply for the zone panel-these systems are working without any other modifications. Just my 2 cents.


I was considering doing the same thing. The UPS units designed for servers have a frequency tolerance of +/- .5 hertz. What do you mean by double conversion UPS?
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murphy
Redoak 3046;n59785 wrote:


I was considering doing the same thing. The UPS units designed for servers have a frequency tolerance of +/- .5 hertz. What do you mean by double conversion UPS?


A double conversion UPS rectifies the incoming power to DC. The DC charges the battery and feeds to an inverter that generates the AC output. The output frequency and voltage is not related to the incoming frequency and voltage. A standard UPS only uses an inverter to generate the output power from the battery when the incoming power has failed.
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Redoak 3046
So you’re saying that in a double conversion UPS the inverter runs all the time? Otherwise I don’t see the difference. Any UPS I’ve dealt with takes incoming AC, rectifies it to charge the batteries that power the inverter when AC fails.
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UPS
Redoak 3046;n59790 wrote:
So you’re saying that in a double conversion UPS the inverter runs all the time? Otherwise I don’t see the difference. Any UPS I’ve dealt with takes incoming AC, rectifies it to charge the batteries that power the inverter when AC fails.


These are also referred to as online UPS's. The incoming AC does keep the batteries charged, but the inverter runs all the time to supply the load. Therefore the load never is connected directly to the line, does not see any line noise or fluctuations, and there is no transfer needed when the AC line fails:

[url]https://www.upsbatterycenter.com/blog/what-is-a-online-ups/[/url]



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Redoak 3046
UPS;n59791 wrote:


These are also referred to as online UPS's. The incoming AC does keep the batteries charged, but the inverter runs all the time to supply the load. Therefore the load never is connected directly to the line, does not see any line noise or fluctuations, and there is no transfer needed when the AC line fails:

[url]https://www.upsbatterycenter.com/blog/what-is-a-online-ups/[/url]


Ok, that makes sense. I always thought the inverter came on only when AC was lost. So if the inverter runs constantly what is the life of the UPS? Why not just filter and condition the utility power, which is typically pretty clean and have the inverter run during power failure?


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murphy
For most UPSs the inverter does run only during a power failure. The double conversion or online UPS is the only one where the inverter runs all of the time. With a regular UPS you can filter all you want but you can't remove changes in frequency. The frequency of my old 7 kW generator varied from 62.5 Hz to 58.5 Hz as a function of load. Feeding its output through an online UPS guaranteed that the load on the UPS only saw 60 Hz. They cost more but they solve the problem where frequency stability is required.
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Redoak 3046
Do you have a recommendation on one? I’ve used the Minuteman units on a number of applications and they seem to work well. As far as I know the inverter only runs during utility power loss. Thanks.
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murphy
I only have one online UPS. It is a Minuteman model ED1500RM2U. It is 1500 VA.. The inverter runs all of the time. All of my other UPSs are the type that only run the inverter during a power failure.
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