Home › Electrical Engineering Forum › General Discussion › CALCULATION OF KVA RATING OF WELDING T/F WITHOUT NAME PLATE
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2011/06/16 at 4:16 pm #10518adminKeymaster
DEAR ENGINEERS
CAN YOU GIVE ME A SUITABLE WAY TO CALCULATE THE KVA RATING OF A WELDING MACHINE HAVING NO NAME PLATE
ALSO HOW CAN WE UNDERSTAND THE CAPACITOR CONNECTED IN COMBINATION WITH A POWER EQUIPEMENT IS PROPERLY WORKING?
2011/06/29 at 5:24 pm #12235Sunny BoyParticipantHi
If there is a transformer in your welding machine you may calculate transformers power. I found one very approximate equation for calculating real power of a transformer.
P=A*A, where A is cross section of transformers core.
I usually test capacitors with current clamps. I use Fluke 345 which can actually measure the amount of active and reactive power consumed by a capacitor. You can compare measured data with data on capacitors nameplate.
If you have ordinary clamp meter you may assume that all current is reactive. With use of reactive current, voltage and nominal capacity you can calculate actual reactive power of capacitor. But note that capacitors power is proportional to voltage squared (U*U).
I hope that this information is useful.
Best regards,
Miha
2011/06/29 at 8:08 pm #12237adminKeymasterSunny Boy said:
Hi
If there is a transformer in your welding machine you may calculate transformers power. I found one very approximate equation for calculating real power of a transformer.
P=A*A, where A is cross section of transformers core.
I usually test capacitors with current clamps. I use Fluke 345 which can actually measure the amount of active and reactive power consumed by a capacitor. You can compare measured data with data on capacitors nameplate.
If you have ordinary clamp meter you may assume that all current is reactive. With use of reactive current, voltage and nominal capacity you can calculate actual reactive power of capacitor. But note that capacitors power is proportional to voltage squared (U*U).
I hope that this information is useful.
Best regards,
Miha
G S DAS said:
DEAR ENGINEERS
CAN YOU GIVE ME A SUITABLE WAY TO CALCULATE THE KVA RATING OF A WELDING MACHINE HAVING NO NAME PLATE
ALSO HOW CAN WE UNDERSTAND THE CAPACITOR CONNECTED IN COMBINATION WITH A POWER EQUIPEMENT IS PROPERLY WORKING?
Measure the current and voltage.
kVA = volts x amps. 1phase
kVA = 1.732 x volts x amps – 3phase
2011/06/30 at 7:26 am #12241ramzy2006ParticipantDear
For the above mentioned, the situation depend on if you have electric measuring instrument or not, if yes what you have then you can decide
In a present of jus clamp meter you can measure the current and volt
KVA =V*I
If you have just multimeter reading ohm and volt
You can calculate the resistance of the welding machine direct=R
Then
KVA = V2/R
2011/10/08 at 1:53 pm #12547adminKeymasterWelding Machine commonly rated in amperes. And most of welding machine have 50V secondary winding or use a volt meter to measure it exactly. To calculate the kVA=(ampere rating x secondary voltage) / 1000.

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