208 to 230 in small commercial

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ayven

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Location
Canada
Occupation
electrician
My friend is having a small business- Vet Clinic (we are located in Ontario, Canada)
He has bought a small autoclave with specs:
Total Power: 2000w
Voltage: 1ph 230v
Amperage: 10a
(cord end for 6-15r receptical)

When I came to hook it up, I have found that a system in his clinic has 3 phase 120\208
I have talked to the manufacturer and he informed me that this autoclave has no multi voltage input, so there is no option for 208v.
So what are my options now?

Here is my idea: two hots from panel to Buck/boost transformer (208\230v) phases A+B or B+C or C+A that give me 208 for primary, then from secondary 240v to 6-15R receptical. Thats should work, am I right?
Am I missing something?
P.S.
X-frmr specs:

Transformer Type: Buck/Boost step-up AutotransformerNRTL Listed for United States
Transformer Configuration: Boost (increase)NRTL Certified for Canada
Phase: Single PhaseNEMA 3R Indoor/Outdoor Enclosure
Frequency: 50/60 HzMeets or Exceeds NEMA ST-20 Standards
Input Voltage: 208 V ACBuck and Boost Step-Up Transformer
Primary Amps: 20 A @ 208 V
Primary Configuration: Two winding
kVA: 4.77
Output Voltage: 230 V AC
Secondary Amps: 18.6 A @ 230 V
Voltage Difference: 22 V
Voltage % Difference: 90%
Secondary Configuration: Two winding
 
Or maybe just try it as is. It will generate less heat on 208 but it is probably thermostatically controlled and will still reach design temp. One client of mine has a zillion autoclaves and they take 208 or 240, just the wattage changes, 9kw, 12kw.
 
This was discussed here only a few weeks ago.

Just a note, in a buck/ boost configuration, You're only boosting one leg. It's not really appropriate to say there's a primary and secondary.
 
James L said:
It's not really appropriate to say there's a primary and secondary.
Click to expand...
Within the transformer, it is, but interconnect the primary and secondary, it becomes an auto-transformer.

It works here because there is no need for a neutral, so the line-to-neutral voltages need not match.
 
anyway, at the output Ill have two legs, each of them 120v to ground?
sorry, i just got lost..
 
LarryFine said:
Well, it will measure that way, but that can be misleading to someone with lesser understanding.

It's more accurate to simply say that it increases the line-to-line voltage delivered to the load.
Click to expand...
I disagree. It's best to answer his question and explain why.

If he had any thoughts of "tapping" a convenience plug off one leg, he could mess up some equipment
 
How about:

The voltage between lines is increased, but because the boost is added to only one end of the transformer, and because the source has a grounded neutral, the voltage boost will increase the voltage to ground on only one line.


Hmmm... :unsure:

If one needs a voltage boost that uses the series-connected secondaries, one could separate the two secondaries and wire one at each end of the primary, obtaining the boosted voltage while maintaining a balanced line-to-neutral output.
 
ayven said:
My friend is having a small business- Vet Clinic (we are located in Ontario, Canada)
He has bought a small autoclave with specs:
Total Power: 2000w
Voltage: 1ph 230v
Amperage: 10a
(cord end for 6-15r receptical)

When I came to hook it up, I have found that a system in his clinic has 3 phase 120\208
I have talked to the manufacturer and he informed me that this autoclave has no multi voltage input, so there is no option for 208v.
So what are my options now?

Here is my idea: two hots from panel to Buck/boost transformer (208\230v) phases A+B or B+C or C+A that give me 208 for primary, then from secondary 240v to 6-15R receptical. Thats should work, am I right?
Am I missing something?
P.S.
X-frmr specs:

Transformer Type: Buck/Boost step-up AutotransformerNRTL Listed for United States
Transformer Configuration: Boost (increase)NRTL Certified for Canada
Phase: Single PhaseNEMA 3R Indoor/Outdoor Enclosure
Frequency: 50/60 HzMeets or Exceeds NEMA ST-20 Standards
Input Voltage: 208 V ACBuck and Boost Step-Up Transformer
Primary Amps: 20 A @ 208 V
Primary Configuration: Two winding
kVA: 4.77
Output Voltage: 230 V AC
Secondary Amps: 18.6 A @ 230 V
Voltage Difference: 22 V
Voltage % Difference: 90%
Secondary Configuration: Two winding
Click to expand...
I have used buck boost transformers last 50 years for single & 3 phase. I would take ampere readings on the 3 phase panel and connect it to the 2 phases with the lowest ampere. I never liked running 240 volt motors on a 208 volt system especially in the summer. I have seen motors that have a 240 or 240/480 nameplate stating suitable for 208 volts. Also have to watch running 240 volt heaters on 208 volts. Can not remember the exact # in my old head but if you drop voltage 10% on any heater you drop wattage and the heat produced by atnleast 18%. Won a lunch when a know it prima donna electrician bet m. that a 10' long 240 volt 2000 watt would draw 1000 watts on 120 volts. For a regular induction motor we always sized the transformer at least 25% larger KVA & maybe 40% larger for compressors or installation in a hot location.
 
garbo said:
Also have to watch running 240 volt heaters on 208 volts. Can not remember the exact # in my old head but if you drop voltage 10% on any heater you drop wattage and the heat produced by atnleast 18%. s
Click to expand...
A resistive load rated for 240v uses almost exactly 75% of the power when supplied with 208v.
 
James L said:
No.
1 leg will be 120v to ground
1 leg will be 139v to ground

Like I said, it only boosts 1 leg.
Click to expand...

Got to remember that a modern autoclave is likely fully computerized, as such the power supply is very likely to have MOVs and many MOVs are rated 150v RMS MCOV. If it has a L1-G-L2 MOV and you consider the allowable continuous variation of +/- 5% and occasional allowance of up to +10%, you could have problems with cooking MOVs.
 
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