AC Automatic Voltage Regulator

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drcampbell

drcampbell

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Besoeker2 said:
Then why would there be a higher MCA for the one with the heater? ...
Click to expand...
Because the heating element draws more current than the compressor? (just guessing)

None of these calculations are valid because they've used the 60 Hz run current. When you run a motor on 50 Hz, it will turn 5/6 as fast and consume considerably less power. The compressor motor will consume about 5/6 as much power -- the refrigerant pressure ratio and the torque required to turn the compressor will be about the same at any speed. The fan motor will consume a little more than half as much power -- fan power is a cube function of speed.

A transformer will also need to be derated. The current required to saturate the core -- and its kVA capacity -- will be less at 50 Hz.

Best to send the air conditioner back to North America and use one designed for the local market.
 
Besoeker

Besoeker

Senior Member
Location
UK
drcampbell said:
Because the heating element draws more current than the compressor? (just guessing)

None of these calculations are valid because they've used the 60 Hz run current. When you run a motor on 50 Hz, it will turn 5/6 as fast and consume considerably less power. The compressor motor will consume about 5/6 as much power -- the refrigerant pressure ratio and the torque required to turn the compressor will be about the same at any speed. The fan motor will consume a little more than half as much power -- fan power is a cube function of speed.

A transformer will also need to be derated. The current required to saturate the core -- and its kVA capacity -- will be less at 50 Hz.

Best to send the air conditioner back to North America and use one designed for the local market.
Click to expand...

Good points. I missed the fact that Eqypt, presumably that's where the kit is going to be installed, has a 50Hz supply. The op claims "I have input 220V 60Hz."
 
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Ingenieur

Senior Member
Location
Earth
drcampbell said:
Because the heating element draws more current than the compressor? (just guessing)

None of these calculations are valid because they've used the 60 Hz run current. When you run a motor on 50 Hz, it will turn 5/6 as fast and consume considerably less power. The compressor motor will consume about 5/6 as much power -- the refrigerant pressure ratio and the torque required to turn the compressor will be about the same at any speed. The fan motor will consume a little more than half as much power -- fan power is a cube function of speed.

A transformer will also need to be derated. The current required to saturate the core -- and its kVA capacity -- will be less at 50 Hz.

Best to send the air conditioner back to North America and use one designed for the local market.
Click to expand...

the nameplate lists the FLA
comp 12.2
Heater 13.2
the fan is the same for both at 3.4
 
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I

Ingenieur

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Earth
Besoeker2 said:
But, as drcampbell has pointed out the values for the comp will be different at 50Hz.
Click to expand...

yep, it should go down, making the heater still the largest load

he states ~T is constant
and T = 5252/rpm x P
so if rpm decreases, P must decrease inversely proportional to keep T constant
 
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Ingenieur

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Location
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Besoeker2 said:
SI, not Imperial.
w is omega.
Click to expand...


T = P/w is valid regardless of units (as long as consistent)
I was pointing out the 5252 factor is working in Imp units (rpm, HP)
w = 2 Pi n, n = rev/sec

the 5252 conversion factor is useful in the States since most motors are speed rated in rev/min (rpm) and HP for power
 
Besoeker

Besoeker

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Location
UK
Ingenieur said:
T = P/w is valid regardless of units (as long as consistent)
I was pointing out the 5252 factor is working in Imp units (rpm, HP)
w = 2 Pi n, n = rev/sec
Click to expand...
It's radians per second which is not an Imperial unit.

Now, please can we get back on topic and look at the OP's question?
He's got the wrong voltage and frequency for the kit he wants to power.
What do you suggest he does?
 
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Ingenieur

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Location
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Besoeker2 said:
It's radians per second which is not an Imperial unit.

Now, please can we get back on topic and look at the OP's question?
He's got the wrong voltage and frequency for the kit he wants to power.
What do you suggest he does?
Click to expand...

rad/sec is universal

you can do the same thing in SI units
P (kw) = T (N-m) x rev/min / 9549.3
if T = 5 N-m
and rpm 1425 rpm
P = 5 x 1425 / 9549.3 = 0.746 kW (1 HP)

9549.3 = 1000 w/kw / (2 Pi rad/rev / 60 sec/min)

email mfg
ask how much the unit is derated on 50 Hz, likely not much
the max power htg is still the same since it's resistance htg (perhaps a bit lower due to fan) at 1.9 kva or less
and the power when clg is even less since the comp draws less, ~1.6 kva
get the next standard size up from 2 kva (2.3 kva (?)) and let her rip
 
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Besoeker

Besoeker

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Location
UK
Ingenieur said:
rad/sec is universal
Click to expand...
It's the SI unit for angular velocity.

My reading of the situation is that the OP has an unsuitable unit for his application.
Wrong voltage, wrong frequency.

We don't seem to have information about how he came to have this piece of kit. Of course there are solutions that could make it work at nameplate ratings. But probably simpler and cheaper to get an aircon unit designed for his supply voltage and frequency.
 
I

Ingenieur

Senior Member
Location
Earth
Besoeker2 said:
It's the SI unit for angular velocity.

My reading of the situation is that the OP has an unsuitable unit for his application.
Wrong voltage, wrong frequency.

We don't seem to have information about how he came to have this piece of kit. Of course there are solutions that could make it work at nameplate ratings. But probably simpler and cheaper to get an aircon unit designed for his supply voltage and frequency.
Click to expand...

aren't motors in the UK (and Europe) rated in rpm and kW?

if the cost of exchange > cost of transformer, hook her up and run
I wonder if there is a wall wart that will do this? (euro to US convertor)
https://voltage-converter-transform...t-step-down-voltage-transformers-ce-certified

https://jet.com/product/detail/af20...605942_pla-161921180700:na:na:na:2&code=PLA15
 
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Besoeker

Besoeker

Senior Member
Location
UK
Ingenieur said:
aren't motors in the UK (and Europe) rated in rpm and kW?
Click to expand...
And in most of the rest of the world but I'm not sure what point you are trying to make.
No problem.

Ingenieur said:
if the cost of exchange > cost of transformer, hook her up and run
Click to expand...
But you still have the frequency disparity.

Ingenieur said:
I wonder if there is a wall wart that will do this? (euro to US convertor)
Click to expand...
I think, that for this application, we are a bit beyond what wall warts can achieve.
 
I

Ingenieur

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Besoeker2 said:
And in most of the rest of the world but I'm not sure what point you are trying to make.
No problem.


But you still have the frequency disparity.


I think, that for this application, we are a bit beyond what wall warts can achieve.
Click to expand...

the point: calcs are required regardless, a constant makes it easier

the freq lowers power but torque should remain ~ the same, minimal performance impact (none on heating)

the links are 3 kw plug in converters (basically a xfmr) ~$75
 
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