Heat treatment machine power supply issue 2

[Emad Shaaban]

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

 

[Emad Shaaban]

I don’t think I could ever find anything as clear and straightforward as this. Thank you so much, @waross — you’ve explained it in a way that perfectly aligns with my limited background on the topic.


Many thanks to everyone for the valuable information and advice shared

 

[waross]

A quick note on voltage reduction by auto-transformer.
There are two possible connections.
1. The buck connection where the secondary connections are reversed so as to subtract the secondary voltage rather than adding it.
2. The conventional auto-transformer connection where the higher voltage is connected to the end of the secondary winding and the lower voltage is pulled from the junctions of the primary windings and the secondary windings. In this case, the secondary winding carries both the load current and the primary current.
Despite that it is often preferred to the buck connection. The greatest use in North America is converting from 480 Volts t0 600 Volts and from 600 Volts to 480 Volts.
The most used transformers are 120v:480V. The buck connection would require a less common 600V:120V transformer.
Also, in the plant with the mix of 480 Volts and 600 Volts, we always had on hand 480:120 Volt transformers which could be used either way.

 

[Emad Shaaban]

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.

I have been able to find 25kv 380v/220v transformer
I wanted to double check that using and this 3ph transformer as open delta instead of
Using 2 conventional single phase transformer can make the job is done .

 

[waross]

Doubtful.
Wye or Delta?

 

[Emad Shaaban]

Doubtful.
Wye or Delta?

D/Y 440/220v . I will open the interconnections and make the adjstment for open delta connection

 

[waross]

Nowhere has frequency been mentioned.
A 470-575Volt machine intended for 60 Hz may not survive 480 Volts at 50 Hz.

 

[Emad Shaaban]

Nowhere has frequency been mentioned.
A 470-575Volt machine intended for 60 Hz may not survive 480 Volts at 50 Hz.

The machine can work at 50/60hz base on its name plate