Download Three phase load calculations

Thy select iss 2 US new
10/25/00
2:29 PM
Page 12
Single Phase Load Calculations
IL
VL
=
Line to line voltage
IL
=
Line current
P
=
Total power
RL
=
Load resistance
cos∅ =
VL x IL x cos∅
P=
IL=
VL
RL
For resistive loads, cos∅=1.0
RL
VL
Power factor
Three phase load calculations
VL
=
Line to line voltage
VP
=
Phase voltage
IL
=
Line current
IP
=
Phase current
P
=
Total power
cos∅ =
Delta Connected Load
IP
IL
VL
VL
IL
VP
VL
Neutral
IL
IP
VP
VL
I
neutral
VP
VL
IP
IL
IP
IL
VP
VL
Power factor
Wye Connected Load
VP
IP
VP
IP
IL
IL =IP
VL =VP
Quick Formula
For a balanced delta connected
load only:
For a balanced wye connected
load only:
IL = 3 x IP
P = 3 x VL x IL x cos∅
P = 3 x VL x IP x cos∅
For resistive loads, cos∅ = 1.0
VL = 3 x VP
P = 3 x VL x IL x cos∅
P = 3 x VP x IL x cos∅
For resistive loads, cos∅ = 1.0
To determine the line current (in Amps)
for balanced 3-∅ resistive loads
(wye- or delta connected)
where P = total 3-∅ power in kW:
for VL =480V
for VL =240V
for VL =208V
IL = 1.2 x P (in kW)
IL = 2.4 x P (in kW)
IL = 2.8 x P (in kW)
© Copyright Eurotherm Controls Inc 2000
All rights strictly reserved. No part of this document may be
stored in a retrieval system, or any form or by any means
without prior written permission from Eurotherm Controls Inc.
Every effort has been taken to ensure the accuracy of this
specification. However, in order to maintain our technological
lead we are continuously improving our products which could,
without notice, result in amendments or omissions to this
specification. We cannot accept responsibility for damage,
injury, loss or expenses resulting therefrom.
HA136393 Issue 2