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Member

Join Date: Jul 2007
Posts: 9

# Cable Type & Sizing Required For Welding Machines

08/10/2007 7:51 AM

Can someone help me in deciding correctly the cable type and sizes required for the input and output of following welding machines:

1. Submerged Arc Welding m/c: (Inverter based)

Rating: 55 kVA,

Current range: 60 – 1250 A,

Open circuit Voltage: 75 V

Full Load pf: 0.95

Duty cycle: 100%

1. MIG Welding m/c: (Inverter based)

Rating: 17.2 – 22.5 kVA,

Current range: 340 – 400 A,

Open circuit Voltage: 18 – 54 V

Full Load pf: 0.95

Input Current: 35 A

1. Welding Rectifier m/c:

Rating: 18.4 kVA,

Current range: 60 – 1250 A,

Open circuit Voltage: 75 V

Full Load pf: 0.95

Duty Cycle- 100%

Thanks

Pathfinder Tags: cable sizing Welding Machines
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Guru

Join Date: Dec 2006
Location: Long.92E,Lat.26N
Posts: 1336
#1

### Re: Cable Type & Sizing Required For Welding Machines

08/11/2007 2:08 AM

55KVA or 22.5

3Φ or 1Φ?

fOR 3PH 55000=√3. EL..IL . cosΦ (=0.95) . Knowing EL - SAY 420V you get ILAmps.

Rule of Thumb for light insulation thickness in free air =1000 Amp/mm2 You get section in Aluminium

Likewise for1phase

Member

Join Date: Jul 2007
Posts: 9
#2
In reply to #1

### Re: Cable Type & Sizing Required For Welding Machines

08/11/2007 2:28 AM

All eqpts are 3 phase.

For 55 KVA, IL = approx. 75-80 Amps. This is OK. However, what is the reason for assuming pf = .95. Is it not true that pf is generally poor for welding machines?

Also, could u throw some more light on this thumb rule of 1000 Amps/mm2??? (1000 Amps??) (eg. 90 mm sq. cable is normally rated for around 130 Amps? then how come 1000 amps / mm sq?)

Guru

Join Date: Dec 2006
Location: Long.92E,Lat.26N
Posts: 1336
#3
In reply to #1

### Re: Cable Type & Sizing Required For Welding Machines

08/11/2007 12:54 PM

< =1000 Amp/mm2 >

0ops!! Meant 1000A/inch2 Or~ 1.5A /mm2