What is the minimum acceptable voltage on a 208/230v 1ph condenser? Customer has a unit with a static 206v and the compressor is unable to start if there is any residual head pressure on the system causing some breaker trips on hot days.
Minimum incoming voltage?
redstone85
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What is the minimum acceptable voltage on a 208/230v 1ph condenser? Customer has a unit with a static 206v and the compressor is unable to start if there is any residual head pressure on the system causing some breaker trips on hot days.
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Compressor says 208-230 1PH.
Voltage drops as low as 198 on start up.
My question is would we call 208 +/- 10% good? Or is 208 the MINIMUM voltage?
I stumbled across this from a motor repair company's website...
"Some commercial customers have converted their building services from 240 volts 3-wire to 208Y/120 volts 4-wire. Seeing nameplates on equipment (especially HVAC) reading “208- 230” or “208/230” volts, they’ve assumed “no problem.” When motor failures then occurred, the complaint was “low voltage.” What’s the story?
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Standard motors are designed and nameplated “230” (or 230/460) volts. That means the minimum permissible terminal voltage (not back at the controller, or service entrance) is 90% of 230, or 207 volts.
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But suppose the same motor is connected to a “208 volt” system. The ANSI standard then allows minimum service entrance voltage of 191; 184 is permitted at the motor. Those values are well below the 207 volt level. That forces the motor current way up, so that the motor is likely to overheat, and is no longer warranted for normal performance or life expectancy. So what’s the meaning of equipment nameplates reading “208-230” or “208/230” volts? No such markings appear in any standard. All they mean, in commercial practice, is that the basic motor design (most often made for 230 volts) is satisfactory at a terminal voltage of 208 – no less. That’s not the same as saying “OK for use on a 208 volt system,” where supply voltage can dip well below what the motor will tolerate."
Voltage drops as low as 198 on start up.
My question is would we call 208 +/- 10% good? Or is 208 the MINIMUM voltage?
I stumbled across this from a motor repair company's website...
"Some commercial customers have converted their building services from 240 volts 3-wire to 208Y/120 volts 4-wire. Seeing nameplates on equipment (especially HVAC) reading “208- 230” or “208/230” volts, they’ve assumed “no problem.” When motor failures then occurred, the complaint was “low voltage.” What’s the story?
...
Standard motors are designed and nameplated “230” (or 230/460) volts. That means the minimum permissible terminal voltage (not back at the controller, or service entrance) is 90% of 230, or 207 volts.
...
But suppose the same motor is connected to a “208 volt” system. The ANSI standard then allows minimum service entrance voltage of 191; 184 is permitted at the motor. Those values are well below the 207 volt level. That forces the motor current way up, so that the motor is likely to overheat, and is no longer warranted for normal performance or life expectancy. So what’s the meaning of equipment nameplates reading “208-230” or “208/230” volts? No such markings appear in any standard. All they mean, in commercial practice, is that the basic motor design (most often made for 230 volts) is satisfactory at a terminal voltage of 208 – no less. That’s not the same as saying “OK for use on a 208 volt system,” where supply voltage can dip well below what the motor will tolerate."
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This of course is just my opinion, I would say, anything below 208 is not good, and I personally believe the mfg. would agree.
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Nameplate says 208-230 and there is no manual to be found. Unit is a chinese made Midea unit, 24v side discharge condenser. If the voltage says 230 or 208 then the +/- 10% is standard to my knowledge but when the name plate says 208-230 is it 208 +/- 10%, 230 +/- 10% or anywhere between 208-230 should be fine is the question.
The customer is getting contradictory information from "electrical engineer" neighbors and I want to be sure of myself before I push back.
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Not disagreeing with you here, but is there some documentation from the compressor/compressors mfg. that says this?
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"...motors are sold and warranted for voltages no lower than 10% under the value on the motor nameplate. This is a NEMA requirement."
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I understand, and I’m not even from Missouri “show me state” but can you provide some documentation or even a link to something that says that from the manufactures.
I would just like to see where the manufactures say that it’s OK to run their equipment at a 10% lower voltage than it says on the nameplate of whatever they manufacture that’s all I would like to see.
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Cant post pictures but the installation manual for a Rheem RA13 states that the minimum/maximum voltage for a 208/230 1phase system is 187-253 which is +/- 10%.
Unfortunately this contradicts what I pulled off the motor repair companies website in the post above. Which leaves me back at square 1.
Unfortunately this contradicts what I pulled off the motor repair companies website in the post above. Which leaves me back at square 1.
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I’m a Ruud dealer, so I should be able to find this information pretty easy.
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I kind of get the impression that every manufacturer has their own rules. I've always had 10% over/ 5% under stuck in my head, and many package units will have 197 and 253 listed as minimum and maximum allowable voltages. Personally I'd start howling at the power company if I ever saw my house power drop that low
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Is this on a mini-split? What has the manufacturer said?
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197 - 253. The 10% is calculated from 230 volt. Post a picture of the unit label. That is typically on there.
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