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2.24kW Pedestal Grinder - protection

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ekuegler

Electrical
Jan 2, 2012
38
GB
Wondering if anyone can help me out, we have a 2.24kW pedestal grinder supplied at 440/60/3 - 0.85p.f - would using a 2.5mm2 SWA cable to supply be adequete with a 10A MCB protecting the cable.

calculated the 3 phase current to be 3.5A - anyone suggest/comment on the cable/MCB used. Are these acceptable???
 
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I don't know what kind of MCB it is provided but usually it will trip for 3*Irated in 10 sec that means if the induction
motor rated current is 3.5 A at start [or at locked rotor situation] the MCB will not trip in less than 10 sec.
From BS 5467 the continuous load current for 3*2.5 sqr.mm SWA[copper conductor] -ampacity will be 31 A [cable supported by clips at 30 dgr.C ambiant.
This is more than LRC[Locked Rotor Current] let's say 3.5*7=24.5 A
The Voltage drop at start=16 MV/A/m *25 A will be 15% for not more than 150 m cable.
See:
 
ABB MCB is type S203MC10, 3 pole, 10A, 10KA, C Curve. In essence the set up I.e , ABB 10A MCB, 2.5mm2 3core SWA to supply a grinder rated at 440/3/60 2.24kW is adequate......?

 
If the cable length is not more than 150 m this cable is adequate.
The MCB is adequate anyway.
 
One other question, would this set up still be adequate for use on an IT or floating earth system, given the fact the system can still run with 1 such fault!
 
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