UPS sizing

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hhsting

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I have 1/3 HP, 120V sump pump full load amps is 4.1A Class A. This is the only load in UPS.

locked rotor current would be 24.6A. The emergency UPS would be 3kVA.

However if one sizes the ups by full load amps then it would be 500vA.

Question:

1. UPS sizing for such a pump should it take into account locked rotor current or just the full load amps?

2. How long should the UPS run anyone have idea?
 
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One UPS manufacturer says this:
"If you are running a motor load, you must take the locked rotor current of the motor (in amps) and multiply it by the mains voltage (120 in this case) to get the MINIMUM rating of the UPS in VA. You must pay strict attention to this safety margin consideration when considering which UPS to use for reliable performance to occur"

How long the UPS can run the motor will be based on the ampere hour rating of the batteries in the UPS. One 3kVA UPS says it can supply full load for 3 minutes and half load for 9 minutes. You will be about 17% load, so maybe 30 minutes or so. If it has to run very long you will need to look at one that has provisions to connect external batteries to extend the run time.
 
don_resqcapt19 said:
One UPS manufacturer says this:
"If you are running a motor load, you must take the locked rotor current of the motor (in amps) and multiply it by the mains voltage (120 in this case) to get the MINIMUM rating of the UPS in VA. You must pay strict attention to this safety margin consideration when considering which UPS to use for reliable performance to occur"

How long the UPS can run the motor will be based on the ampere hour rating of the batteries in the UPS. One 3kVA UPS says it can supply full load for 3 minutes and half load for 9 minutes. You will be about 17% load, so maybe 30 minutes or so. If it has to run very long you will need to look at one that has provisions to connect external batteries to extend the run time.
Click to expand...

Their is no soft start with ups that could limit the locked rotor current?
 
hhsting said:
I have 1/3 HP, 120V sump pump full load amps is 4.1A Class A. This is the only load in UPS.

locked rotor current would be 24.6A. The emergency UPS would be 3kVA.

However if one sizes the ups by full load amps then it would be 500vA.

Question:

1. UPS sizing for such a pump should it take into account locked rotor current or just the full load amps?

2. How long should the UPS run anyone have idea?
Click to expand...
Your use of the word "emergency" makes me ask if it really is an article 700 source or just a backup? If it is truly is needed for Article 700, you are stuck at 1-1/2 hours per 700.12(C)(4) Storage Batteries and UPS.
 
ron said:
Your use of the word "emergency" makes me ask if it really is an article 700 source or just a backup? If it is truly is needed for Article 700, you are stuck at 1-1/2 hours per 700.12(C)(4) Storage Batteries and UPS.
Click to expand...

I think it can identify as optional standby
 
ron said:
Your use of the word "emergency" makes me ask if it really is an article 700 source or just a backup? If it is truly is needed for Article 700, you are stuck at 1-1/2 hours per 700.12(C)(4) Storage Batteries and UPS.
Click to expand...
That rule only applies to storage batteries and UPS used for emergency lighting. The general rule in 700.12(C) would apply to the supply to the pump, if this is an Article 700 installation. That general rule requires 2 hours.
 
Wouldn't it be better to add a battery operated backup sump pump? Then you can have as big of a string of 12v flooded batteries as you want....
Computer UPSs typically don't like motor loads, especially if the motor is the only load on it.
 
Todd0x1 said:
Wouldn't it be better to add a battery operated backup sump pump? Then you can have as big of a string of 12v flooded batteries as you want....
Computer UPSs typically don't like motor loads, especially if the motor is the only load on it.
Click to expand...


Can this pump have 12v backup battery or not? It is already installed

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You can go to APC.com and there is a "get help" link. They will help you select the correct unit.
 
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