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Heat treatment machine power supply issue 1

Emad Shaaban

Emad Shaaban

Electrical
Jun 26, 2017
28
Hi every one
A heat treatment machine (pro heat 35) works with power supply 470v/575v..please see attachment
What options I have to make this machine works on 380v power supply
 

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Best for temporary or low-budget solutions: sse a Step-Up transformer. ​

 
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What if user the standby 380v generator and then increase its excitation,will that affect winding withstanding?
 
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Emad Shaaban said:
What if user the standby 380v generator and then increase its excitation,will that affect winding withstanding?
Click to expand...
You have to check the generator nameplate to see if 480 Volts is an available voltage.
It may need a change in the connections and it will need an adjustment of the AVR.
Another issue with the generator is the maximum Volts-per-Hertz of the windings.
If you try for a voltage much above the rated V/H, saturation will limit further increases of voltage.
And, the voltage based on the V/H At 60 Hz is 6/5 times the maximum voltage at 50 Hz.
You may have to adjust the governor up to 60 Hz.
While reconfiguring the generator is most likely possible it is not a simple adjustment.
Your best option is a pair of 380:110 (or the closest available ratings) transformers configured as an open delta auto-transformer.
 
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Thank you every one, I tried to find 380/480v step up transformer ,but it seem to be unavailable on the local markets on my region.
Can you please suggest other options please
 
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Read my bLIPs;
Your best option is a pair of 380:110 (or the closest available ratings) transformers configured as an open delta auto-transformer.
Click to expand...
Pit falls:
Volts per Hertz.
380 Volts suggests 50 Hz.
60 Hz transformers used on 50 Hz must have the maximum allowable voltage reduced in the ratio of 50Hz/60Hz to avoid magnetic saturation.
With a maximum voltage of 575 Volts you may consider limiting 50 Hz voltage to 489 Volts.

Try a 480 Volt to 120 Volt single phase transformer configured as an auto-transformer.
480V + 120V = 600V
600v x (380V/480V) = 475 Volts. (600V x (50Hz/60Hz) = 500 Volts = Safe from saturation.

Capacity:
Assume 40 Amps.
120 Volts x 40 Amps / 1000 = 4.8 KVA minimum.
Substitute your current and do the math to determine the needed capacity.
Two such transformers are needed.
Open delta, auto-transformer boost connection.
I have used this solution many times going from 480 Volts to 600 Volts and a similar solution going from 600 Volts to 480 Volts.
 
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Thanks everyone,thanks waross.
Actually my application is to step up 380v /480v
please excuse my limited experience,
3ph 380/110 transformer is available .it not single cores.
I need to be fully aware of connection .I should be very appreciative if can be sketched for me
 
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Fun with numbers:
Boost 380 Volts to 490 Volts.
What transformer capacity is needed for a 50 Amp load?
Three phase transformer: 50 A x 490 V x 1.73 / 1000 = 42.4 KVA x one transformer
Three single phase transformers: 50 A x 283 V / 1000 = 14.15 KVA x three transformers.
Two auto-transformers in open delta: 50 A x 110 V = 5.5 KVA x two transformers. 380V:110V transformers.
Total transformer capacity needed:
Conventional transformers = 42.4 KVA
Open delta auto-transformer = 11 KVA
Check the prices.
 
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Thank you(WAROSS) very much with all respect for your time and efforts .that was very supportive .
 
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Thank you for the thank you.
Anecdotally when I worked for a contractor in Western Canada, we had a customer with a 480 Volt service.
In Eastern Canada they had a similar plant with a 600 Volt service.
They would frequently sent 600 Volt equipment out west and it was my job to spec and plan the transformers.
Then they built a new plant. BC had changed the standard voltage up to 600 Volts.
The new plant had two MCCs, one at 480V, one at 600V.
They used a two transformer auto-transformer set to drop from 600V to 480V.
But if a location was fed from one MCC it could not be changed to feed from the other MCC.
Then they started switching equipment around.
Over half of the time, there was a voltage change.
I had pairs of transformers sitting beside equipment all over the plant going from either 480 V to 600 V or from 600 V to 480 V.
My suggestion is not based on book theory.
It is based on a lot of successful field experience.
Good luck.
 
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Impressive experience.I will get it started and keep my experience posted here.Thanks again
 
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Rental companies supplying the oil industry in Western Canada have both open delta and full wye autotransformers available for rent.
Many petro-chemical plants have 600 Volt systems. Almost all rental generators are 480 Volts.
When a 600 Volt plant needs temporary power, they rent a 480 volt to 600 Volt auto-transformer along with the 480 Volt generator.
 
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Emad Shaaban said:
Hi every one
A heat treatment machine (pro heat 35) works with power supply 470v/575v..please see attachment
What options I have to make this machine works on 380v power supply
Click to expand...
Hello! According to the Pro Heat 35 electrical diagram you posted (see 460–575 V or CE unit 400–460 V power supply instructions), direct driving at 380 V power supply will be lower than the rated voltage range of the machine, which may easily lead to:

Insufficient motor torque and unstable operation

Control board/contactor life reduction or even malfunction

Insufficient heating element power and difficult to meet the heat treatment temperature standard

To use it safely and reliably at 380 V, there are several feasible solutions:

1. External step-up transformer (Autotransformer/three-phase isolation transformer)

Principle: Boost 380 V to the 400–460 V range required by the machine

Advantages: Simple solution, one-time investment, almost no change to the internal wiring of the machine

Note: When selecting, you need to select sufficient capacity according to the maximum power (kW) of the machine (usually leave 10% margin); and ensure that the three-phase balance of the transformer

2. Use a three-phase variable frequency drive (VFD) with a step-up function

Principle: First, 380 V is rectified into DC, and then inverted to output AC above 460 V

Advantages: It can achieve speed regulation/soft start at the same time and reduce impact; the output voltage can be adjusted online to adapt to more working conditions

Note: Make sure that the selected VFD supports the "voltage boost (Boost)" or "variable frequency boost" function, and configure the output parameters

3. Static frequency converter

Principle: Similar to VFD, but more focused on voltage boost/reduction and stable output, the cost is between transformer and VFD

Advantages: small size, high efficiency; small impact on the power grid

Note: When purchasing, make sure that the continuous power and peak power can meet the startup and operation requirements of Pro Heat 35
 
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grandpackmachine said:
Hello! According to the Pro Heat 35 electrical diagram you posted
Click to expand...
You may find it educational to read other posts before posting.
A number of your suggestions may be a little off.
One instance;
grandpackmachine said:
Note: When selecting, you need to select sufficient capacity according to the maximum power (kW) of the machine (usually leave 10% margin); and ensure that the three-phase balance of the transformer
Click to expand...
By far the cheapest, both cost of material and labour, is the open delta auto-transformer boost.
Capacity depends on KVA, not kW.
This connection inherently causes a slight unbalance that is immaterial in practice.
 
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grandpackmachine said:
Hello! According to the Pro Heat 35 electrical diagram you posted (see 460–575 V or CE unit 400–460 V power supply instructions), direct driving at 380 V power supply will be lower than the rated voltage range of the machine, which may easily lead to:

Insufficient motor torque and unstable operation

Control board/contactor life reduction or even malfunction

Insufficient heating element power and difficult to meet the heat treatment temperature standard

To use it safely and reliably at 380 V, there are several feasible solutions:

1. External step-up transformer (Autotransformer/three-phase isolation transformer)

Principle: Boost 380 V to the 400–460 V range required by the machine

Advantages: Simple solution, one-time investment, almost no change to the internal wiring of the machine

Note: When selecting, you need to select sufficient capacity according to the maximum power (kW) of the machine (usually leave 10% margin); and ensure that the three-phase balance of the transformer

2. Use a three-phase variable frequency drive (VFD) with a step-up function

Principle: First, 380 V is rectified into DC, and then inverted to output AC above 460 V

Advantages: It can achieve speed regulation/soft start at the same time and reduce impact; the output voltage can be adjusted online to adapt to more working conditions

Note: Make sure that the selected VFD supports the "voltage boost (Boost)" or "variable frequency boost" function, and configure the output parameters

3. Static frequency converter

Principle: Similar to VFD, but more focused on voltage boost/reduction and stable output, the cost is between transformer and VFD

Advantages: small size, high efficiency; small impact on the power grid

Note: When purchasing, make sure that the continuous power and peak power can meet the startup and operation requirements of Pro Heat 35
Click to expand...
Thank you indeed for you engagement.
I’m afraid of that VFDs does not give a smooth sinusoidal wave but a square wave that can properly run an induction load but not electric
I decided to go with option suggested by Eng @ waross by implementing an open delta auto transformer
 
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waross said:
Rental companies supplying the oil industry in Western Canada have both open delta and full wye autotransformers available for rent.
Many petro-chemical plants have 600 Volt systems. Almost all rental generators are 480 Volts.
When a 600 Volt plant needs temporary power, they rent a 480 volt to 600 Volt auto-transformer along with the 480 Volt generator.
Click to expand...
I just wanted to confirm that with autotransformers, I don't need to meet the full kVA of the equipment, on the rated amps times the difference in voltage.
I mean what’s the minimum suggested TR size to handle the 37kw
 
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Take the rated KVA times 1000.
Divide by the rated secondary voltage to get the rated secondary current.
The rated secondary current must be equal to or greater tha the losd current.

Example:
Transformer Ratings.
10 KVA, 480/120 Volts
10,000 VA / 120 Volts = 83.3 Amps.
The 120 Volt windinhs on a 10 KVA transformer will safely support an 83.3 Amp load.

Use Amps for the load, not KVA nor kW.

Example #2
37 kW at 480 Volts and 0.8
PF = 96 Amps.
96 Amps will flow on the secondary windins of the boost transformers.
96 Amps times 120 Volts = 11520 VA or 11.5 KVA.
In this example you would need aa transformer of 11.52 KVA or greater .
Possibly 125 KVA or 15 KVA.

Warning. This is an example.
Use your own values and do your own calculation s.
 
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