Industrial Control Transformer

[fifty60]

Is there any problem with using an Industrial Control Transformer to supply a single phase fan load only? I normally only use general purpose transformers for this, but there are some space limitations and I can mount these high and dry in an enclosure. The transformer is a CE100TH and can be found at this link:

http://www.solahevidutysales.com/pdf/transformers/ICE.pdf

Any thing I should think of before using this to supply a fan load that will operate at 380V fan at 50Hz and 2Amps?

 

[templdl]

Is there any problem with using an Industrial Control Transformer to supply a single phase fan load only? I normally only use general purpose transformers for this, but there are some space limitations and I can mount these high and dry in an enclosure. The transformer is a CE100TH and can be found at this link:

http://www.solahevidutysales.com/pdf/transformers/ICE.pdf

Any thing I should think of before using this to supply a fan load that will operate at 380V fan at 50Hz and 2Amps?

Comparing the size of the same kva for each transformer why is the cpt smaller?
Also, where are you out sourcing the 50hz and if supplying 60 hz to a fan tasted for 50hz the motor may work OK but will fun faster. In doing so will the fan load be acceptable on the motor at the higher RPM?
Oh, one more thing, since the primary and secondary ratios are not the same for a cpt the unloaded secondary voltage will be higher because the winding ratio is compensated for voltage drops caused by inrush loads of relays. Thus the unloaded secondary voltage will be higher than the actual nameple voltage which may not be relevant in your application.

 

[Bugman1400]

Is there any problem with using an Industrial Control Transformer to supply a single phase fan load only? I normally only use general purpose transformers for this, but there are some space limitations and I can mount these high and dry in an enclosure. The transformer is a CE100TH and can be found at this link:

http://www.solahevidutysales.com/pdf/transformers/ICE.pdf

Any thing I should think of before using this to supply a fan load that will operate at 380V fan at 50Hz and 2Amps?

There is nothing wrong with using this xfmr as long as you are within the VA rating. However, if your source is 60Hz then your 50Hz fan will spin faster than expected.

 

[petersonra]

I agree the xfmr itself will work fine. The fan will run faster. That may or may not be an issue.

 

[Jraef]

As a general rule, the difference between a GP transformer and a Control Power Transformer is that the CPT is designed to deliver higher inrush current for energizing coils without causing saturation and instability. The cost of that capability, other than money, is stability at the far opposite end of the load capacity. It is a general rule that a CPT should not be selected for more than 4x of the expected load. so of your fan is 2A, don't use a CPT rated for more than 8A output. However, since this is a fan, not a coil, and it appears maybe to be the only load on the transformer, voltage stability may not be a big deal anyway.

But as the others said, running the fan 20% faster may be problematic. Centrifugal fans will pull 173% of their rated power at the higher speed if the air flow is not restricted.

 

[Bugman1400]

As a general rule, the difference between a GP transformer and a Control Power Transformer is that the CPT is designed to deliver higher inrush current for energizing coils without causing saturation and instability. The cost of that capability, other than money, is stability at the far opposite end of the load capacity. It is a general rule that a CPT should not be selected for more than 4x of the expected load. so of your fan is 2A, don't use a CPT rated for more than 8A output. However, since this is a fan, not a coil, and it appears maybe to be the only load on the transformer, voltage stability may not be a big deal anyway.

But as the others said, running the fan 20% faster may be problematic. Centrifugal fans will pull 173% of their rated power at the higher speed if the air flow is not restricted.

Where did you hear or read about the 4x load for a CPT? I have not heard that before. Can you provide a link so, I can read up on that?

Thanks.

 

[Jraef]

Where did you hear or read about the 4x load for a CPT? I have not heard that before. Can you provide a link so, I can read up on that?

Thanks.

Well, I used to work for a company that made them, or really, brand labeled them from Hevi-Duty, that's where I learned that. Since being taken over by Emmerson, they are no longer as generous with their information and I couldn't locate a reference from them. You can find indirect references to is on several sites regarding CPTs, but they don't give the numbers, they just warn about it. Here's one:
http://literature.rockwellautomation.com/idc/groups/literature/documents/wp/1497-wp001_-en-p.pdf
Page 5, "Secondary Voltage Considerations"

and
http://www.transfabtms.com/openfile.aspx?file=ind-def-sel-perf-eng.pdf
Page 3

 

[topgone]

Where did you hear or read about the 4x load for a CPT? I have not heard that before. Can you provide a link so, I can read up on that?

Thanks.

Most industrial control transformer manufactures list every product they make with selection charts. One of the important informations they publish are the inrush VA ratings of each of the model segregated according to the expected voltage drop at the CPT terminals.

IIRC, @jraef's figure of "4x" could be referring to the ratio of a certain manufacturer's guaranteed inrush VA to nameplate VA. I was taught this way by a mentor of mine a long time ago when sizing CPTs for control cubicles that he wanted designed. His instructions to me were:
1) to add all relays/contactors sealed VA X 1.25 plus,
2) the sum of all inrush VAs of each control element that could possibly be drawing power at the same instant and
3) then divide the sum total by 4!
That's the nameplate rating of the CPT that will be installed. Hope that helps.

 

[templdl]

Well, I used to work for a company that made them, or really, brand labeled them from Hevi-Duty, that's where I learned that. Since being taken over by Emmerson, they are no longer as generous with their information and I couldn't locate a reference from them. You can find indirect references to is on several sites regarding CPTs, but they don't give the numbers, they just warn about it. Here's one:
http://literature.rockwellautomation.com/idc/groups/literature/documents/wp/1497-wp001_-en-p.pdf
Page 5, "Secondary Voltage Considerations"

and
http://www.transfabtms.com/openfile.aspx?file=ind-def-sel-perf-eng.pdf
Page 3

As an illustration of the PRI to sec winding ratio of a CPT simply feed the sec. as a step up and then measure the voltage at the HV terminals. It will be significantly lower than one would anticipated. My outside salesman got an education when he tried to use a 480-120v CPT as a cheap way to measure voltage with a 120v voltmeter scaled for 480v. He discovered that the meter read a significantly lower voltage than 480v meaning that the actual secondary voltage was greater than 120 with 480v applied to the primary.

 

[fifty60]

Thanks, this was all very helpful. What does CPT stand for?

 

[templdl]

Thanks, this was all very helpful. What does CPT stand for?

Good point. Control power transformer.They differ from general purpose transformers in that when you have a 480 PRI and a 120 Sec you would anticipate a simple 4:1 winding ratio. But with CPTs they have a slightly higher ratio which results is a slightly higher secondary voltage voltage in order to address voltage drops as a result of coil inrushes to pull in relay and contactor coil loads.