commercial oven from overseas

[Ponchik]

I have a client who has a 220V-3phase 70KW electric oven from China that needs to get installed. The building has Y 208-120V system but the actual voltage is 214 Volts between the phases.

The building is vacant and no additional load are connected. i am thinking once the electrical system gets loaded the 214V will drop to more close to 208 or even less.

So, do you think i should install a boost transformer or not worry about it since there isn't much voltage difference?

Thanks for your input.

 

[Ponchik]

If breaker is within site, I don't need a additional disconnect on the 220V side. Do I ?

 

[shamsdebout]

Sometimes some of of these equipment will have a voltage range of 200 volt - 220 volt. I think you would be phone powering this piece of equipment from a 208 volt source. I take it the frequency matches the power source you will be connection it to.

 

[Besoeker]

I have a client who has a 220V-3phase 70KW electric oven from China that needs to get installed. The building has Y 208-120V system but the actual voltage is 214 Volts between the phases.

The building is vacant and no additional load are connected. i am thinking once the electrical system gets loaded the 214V will drop to more close to 208 or even less.

So, do you think i should install a boost transformer or not worry about it since there isn't much voltage difference?

Thanks for your input.

Depends what's all in the oven. For the heating elements the lower voltage might not be two much of a problem - the oven will just take longer to get to temperature.
If there are fans that might be an issue. The supply frequency in China is 50Hz.
Relays and contactors also might be a problem. Your higher frequency and lower voltage is a double whammy for them.

 

[broadgage]

A domestic oven should be fine, many are listed for both 208 and 240 volt operation.

However a loading of 70KW suggests a much larger and more complex appliance, probably incorporating relays, contactors, and motors, as posted above these are likely to be problematic on a higher frequency and lower voltage.

Also double check what voltage system the oven is designed for.
220 volt 3 phase systems (220 volts phase to phase) are not that common. Might be intended for 3 phase 4 wire with 220 volts phase to neutral and 380 volts phase to phase.

 

[Besoeker]

Also double check what voltage system the oven is designed for.
220 volt 3 phase systems (220 volts phase to phase) are not that common. Might be intended for 3 phase 4 wire with 220 volts phase to neutral and 380 volts phase to phase.

That's a good point. The domestic voltage is 220V which infers that three phase is probably 380V_L-L as you suggest.

 

[Ponchik]

A domestic oven should be fine, many are listed for both 208 and 240 volt operation.

However a loading of 70KW suggests a much larger and more complex appliance, probably incorporating relays, contactors, and motors, as posted above these are likely to be problematic on a higher frequency and lower voltage.

Also double check what voltage system the oven is designed for.
220 volt 3 phase systems (220 volts phase to phase) are not that common. Might be intended for 3 phase 4 wire with 220 volts phase to neutral and 380 volts phase to phase.

In the instructions it was stated 3 wire 3 phase 380volts but on the name plate of the unit is 220V, 3 phase 60HZ. I had the owner call and he verified that the unit was specifically built for US market.
Maybe i will call to double check.
But my concerns is if the unit is built for 220V, do i really need to have boost transformers? The relays, motors and contactors do have 10% voltage range anyway.

 

[kbsparky]

If breaker is within site, I don't need a additional disconnect on the 220V side. Do I ?

If the breaker is within sight and on site ​within 50 feet, then no additional disconnect is required.

 

[jeremysterling]

To prevent a call-back, you should well consider your idea to install boost transformers. If you install the oven to the 208V and the bread does not come out of the oven golden brown, you will start tap-dancing. If you install the buck/boost and the bread does not come out golden brown, you can suggest an egg wash or sugar glaze!

 

[growler]

In the instructions it was stated 3 wire 3 phase 380volts but on the name plate of the unit is 220V, 3 phase 60HZ. I had the owner call and he verified that the unit was specifically built for US market.
Maybe i will call to double check.
But my concerns is if the unit is built for 220V, do i really need to have boost transformers? The relays, motors and contactors do have 10% voltage range anyway.

Make sure to get phase rotation right so any motors are turning in the right direction and collect you money on completion or earlier and don't worry about it.

I did a frozen yogurt place where all the equipment was from china and no problems.

One thing I do is use larger conductors to make sure there isn't very much of a voltage drop.

Depending on where you are and the time of day voltages fluxuate so you never have a true 220 or 208 anyway. 208 is close enough to 220 but you could run into trouble if there is a large voltage drop ( so I try to cover as best I can with larger cable than minimum ).

 

[Jraef]

So let's go back to this:

Depends what's all in the oven. For the heating elements the lower voltage might not be two much of a problem - the oven will just take longer to get to temperature.
If there are fans that might be an issue. The supply frequency in China is 50Hz.
Relays and contactors also might be a problem. Your higher frequency and lower voltage is a double whammy for them.

Fans designed for 50Hz running at 60Hz will run 20% faster, but on a fan, that means the air flow will increase the load on the motor at the cube of the speed change, so by an additional 78% and the motors will overload. You may have to either replace the motors (preferred) or otherwise lower the air flow. i.e. a vane control in the duct.

And what he meant by the relay and contactor issue has to do with the coils. In my experience, 50Hz coils, especially CHEAP coils as are what you are likely to find on Chinese equipment, do not last long on 60Hz power systems. They saturate and overheat, then the insulation fails relatively quickly. Look at all of your contactors and coils. If they are common brand names that you recognize and can get here in the US, like Siemens, Telemecanique, ABB etc, then buy 60Hz coils and change them now. If they are Chinese knock-off or just off brands you have never heard of, or the spelling is slightly different (i.e. Seamans), throw them out now and replace them with something you can source locally. Save yourself the call back and headaches.

I love it when people fall so in love with something as mundane as an appliance that they are willing to ship it across the globe, but fail to take the time to investigate AHEAD OF TIME what it will take to use it once it arrives. Just buy locally people...

 

[Ponchik]

So let's go back to this:



Fans designed for 50Hz running at 60Hz will run 20% faster, but on a fan, that means the air flow will increase the load on the motor at the cube of the speed change, so by an additional 78% and the motors will overload. You may have to either replace the motors (preferred) or otherwise lower the air flow. i.e. a vane control in the duct.

And what he meant by the relay and contactor issue has to do with the coils. In my experience, 50Hz coils, especially CHEAP coils as are what you are likely to find on Chinese equipment, do not last long on 60Hz power systems. They saturate and overheat, then the insulation fails relatively quickly. Look at all of your contactors and coils. If they are common brand names that you recognize and can get here in the US, like Siemens, Telemecanique, ABB etc, then buy 60Hz coils and change them now. If they are Chinese knock-off or just off brands you have never heard of, or the spelling is slightly different (i.e. Seamans), throw them out now and replace them with something you can source locally. Save yourself the call back and headaches.

I love it when people fall so in love with something as mundane as an appliance that they are willing to ship it across the globe, but fail to take the time to investigate AHEAD OF TIME what it will take to use it once it arrives. Just buy locally people...

They (the customer) has verified that the oven has been made specifically for U.S. market. My responsibility is to ensure they have the proper voltage to the machine. I am not responsible if the oven does not perform to customer's satisfaction or internal equipment fail prematurely.

I will make sure they understand the contract.

 

[T.M.Haja Sahib]

If you measure and record voltage at the point where you are going to connect the oven over a period of time, you may get a good idea how much actual variation in the voltage is there so that you could provide a suitable voltage regulator to take care of it.

 

[growler]

I have a client who has a 220V-3phase 70KW electric oven from China that needs to get installed.

I had the owner call and he verified that the unit was specifically built for US market.

I have been seeing things like this for years. Thet say it is built for the US Market.

If it is built for the US market then just where in the Good old USA are you going to find three phase 220 power?

Wouldn't it be a lot simplier if someone where to call the Chinese ( after hours phone rate ) and let them know that we use 208 three phase commercial power and that they should design and mark their equipment for 208.

 

[Besoeker]

If you measure and record voltage at the point where you are going to connect the oven over a period of time, you may get a good idea how much actual variation in the voltage is there so that you could provide a suitable voltage regulator to take care of it.

It would for the present loading but adding the extra 70kW might invalidate the readings.

 

[Besoeker]

I have been seeing things like this for years. Thet say it is built for the US Market.

If it is built for the US market then just where in the Good old USA are you going to find three phase 220 power?

Indeed, that struck me as odd too.

Wouldn't it be a lot simplier if someone where to call the Chinese ( after hours phone rate ) and let them know that we use 208 three phase commercial power and that they should design and mark their equipment for 208.

Email might be a better option.. It gets round the difficulties of time difference and language. And you get answers in writing. There's no "That's not what I said."

 

[Jraef]

Email might be a better option.. It gets round the difficulties of time difference and language. And you get answers in writing. There's no "That's not what I said."

I interpreted his response about "call the Chinese" as sarcastic.

I participate in a couple of other more international forums, my impression of Chinese (PRC) engineers is that they really don't investigate anything well, they go by hearsay and anecdotal evidence in their design review process, to a shocking degree. I don't trust anything from off name companies in the PRC, they have nothing to lose by shipping junk. At least when a larger company has products made there, they have their own reputation to lose, so they will exert some QC and typically the design work is NOT done by the PRC job shop.

What we (outside of China) often fail to realize is that with a rising middle class in China, they themselves are now their own huge market place, so they design to that first and foremost. When some exporter sees a product they thing they can sell abroad, the Chinese mfr just tells them whatever they want to hear to make the sale. If it all goes south, it was such a drop in the bucket that they don't even care. The exporter gets left holding the bag, but he just vanishes and starts a new company leaving their agents in foreign countries twisting in the wind. I've seen it time and time again.

Caveat emptor.

 

[suemarkp]

Is this oven UL listed or NRTL tested? If this is going to be installed in Wash/Oregon/California (and the list is increasing), that could be a problem. I don't like that rule here in WA, but it seems to be needed more and more as we get stuff from China (and even some stuff in the US in not immune to some rather shocking safety oversights).

 

[Besoeker]

I interpreted his response about "call the Chinese" as sarcastic.

It might have been. But the owner has evidently called:

I had the owner call and he verified that the unit was specifically built for US market

A 70kW oven is no small piece of kit. If I were the purchaser, I'd want the specification in writing before placing the order. Standard business practice.
As the installer, I'd also want to have sight of that.

I participate in a couple of other more international forums, my impression of Chinese (PRC) engineers is that they really don't investigate anything well, they go by hearsay and anecdotal evidence in their design review process, to a shocking degree.

My experience is a bit different to that based on working with them on projects both there and here.
We also have an office over there and, as it happens, I'm bidding a project for them. It's a set of custom panels, each with a number of DIN rail modules in them. I asked for dimensions

Hi D

Thank you for that.
As ever, dimensions of the modules in real world units would help.

B

The answer came back tacked on to a series of emails going back to March and copied to ten other people.
Not altogether unusual when dealing with them.

I obviously didn't have my brain engaged when I decided to print the dimensions. Send it to the printer and go fetch a coffee.
Fifteen pages later.....
Normally I would have just done a cut and paste of the information I wanted into another document

They seem to like bureaucracy - and plenty of it.

 

[texie]

I interpreted his response about "call the Chinese" as sarcastic.

I participate in a couple of other more international forums, my impression of Chinese (PRC) engineers is that they really don't investigate anything well, they go by hearsay and anecdotal evidence in their design review process, to a shocking degree. I don't trust anything from off name companies in the PRC, they have nothing to lose by shipping junk. At least when a larger company has products made there, they have their own reputation to lose, so they will exert some QC and typically the design work is NOT done by the PRC job shop.

What we (outside of China) often fail to realize is that with a rising middle class in China, they themselves are now their own huge market place, so they design to that first and foremost. When some exporter sees a product they thing they can sell abroad, the Chinese mfr just tells them whatever they want to hear to make the sale. If it all goes south, it was such a drop in the bucket that they don't even care. The exporter gets left holding the bag, but he just vanishes and starts a new company leaving their agents in foreign countries twisting in the wind. I've seen it time and time again.

Caveat emptor.

I wish I could have said it this well. You are right on the money and this is the sad reality.