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Topic Title: Power per phase for a delta motor
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Created On: 28 March 2013 09:39 PM
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 28 March 2013 09:39 PM
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Posts: 79
Joined: 25 January 2011

Originally posted by: MAXMIRA

Hi all,

Can anyone help me I have been given a load schedule for a 35kw delta connected motor. The load schedule shows the 35kw spread across the three phases I.e. 11.66kw per phase. I think this is incorrect as I would put it as 35kw per phase. Can anyone tell me which is the correct method and possibly back it up with some maths. Your help would be much appreciated.


 29 March 2013 10:37 PM
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Joined: 28 October 2011

The formulas for calculating active, reactive, and apparent power in balanced three-phase circuits are the same as those used for single-phase circuits. Since we are considering balanced systems, the total power is three times the power in one phase.
P = P_1 = P_2 = P_3 = V_L I_P cosθ (Power Factor)
Therefore, the total active power P_total dissipated in a three-phase circuit is equal to:
P_total = 3 x P = 3V_L I_P cosθ (PF)
Hence P = P_total/3
P = 35/3 = 11.67 kW
Introduction to AC Circuits

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