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TB161 Rev2 Determining Transformer Size in kVA for a Machine
Overview
This document will help you in determining the size kVA of the transformer that is required for your
machine
Background
In order to determine the total power requirements of your machine you will need to add all of the power
requirements of each individual component that is installed on the machine The components listed in the
tables below consist of standard and some opt ional components that may be installed on a machine If
your machine has a component installed that is not listed below you will need to determine its power
requirements and add it accordingly Once you know the total power requirements of the machine you
just need to apply the formula below to determine the minimum size of the transformer that is required
kVA = kW / PF where PF is the Power Factor which is typically 0 8
Centroid supplied DC system transformer kVA ratings
110VAC Low power transformer 1 86kVA
220VAC High power transformer 2 3kVA
Component Power Rating
Component Power kW
10inlb DC Motor 0 20
17inlb DC Motor 0 35
29inlb DC Motor 0 60
40inlb DC Motor 0 80
35inlb AC Motor 0 75
50inlb AC Motor 1 00
100inlb AC Motor 2 00
150inlb AC Motor 3 00
200inlb AC Motor 4 00
10hp Spindle Motor 7 50
15hp Spindle Motor 11 00
20hp Spindle Motor 15 00
Spindle Chiller 0 95
Swingarm ATC Motor 0 55
Carousel ATC Motor 0 45
Flood Pump 0 75
Lube Pump 0 15
Chip Auger 0 25
Chip Washdown Pump 0 75
Example 1
We have an A532 machine that has a 10hp spindle motor It is a 4 axis machine that is using 2kW AC
motors for X Y and Z and a 750W AC motor for W It also has a spindle chiller swingarm ATC flood and
lube pumps installed on the machine The minimum transformer size that is required is determined in the
table below
Component Power kW
10hp Spindle Motor 7 50
X axis Motor 2 00
Y axis Motor 2 00
Z axis Motor 2 00
W axis Motor 0 75
Spindle Chiller 0 95
Swingarm ATC Motor 0 55
Flood Pump 0 75
Lube Pump 0 15
Total Power kW 16 65
Transformer kVA 20 81
Example 2
We have an A532 machine that has a 20hp spindle motor with a spindle chiller installed It has 2kW AC
motors installed on X and Y axes It has a 4 5kW AC motor installed on Z It also has a tilt table installed
that has 750W AC motors on both the 4th and 5th axes It has a swingarm ATC installed on the machine
It also has a chip auger and flood lube and chip washdown pumps The minimum transformer size that is
required is determined in the table below
Component Power kW
20hp Spindle Motor 15 00
X axis Motor 2 00
Y axis Motor 2 00
Z axis Motor 4 50
A axis Motor 0 75
B axis Motor 0 75
Spindle Chiller 0 95
Swingarm ATC Motor 0 55
Chip Auger 0 25
Flood Pump 0 75
Lube Pump 0 15
Chip Washdown Pump 0 75
Total Power kW 28 40
Transformer kVA 35 50
Example 3
We have a mill with a 10hp spindle motor There are 29inlb DC motors installed on X Y and Z axes It
also has a flood and lube pump installed on the machine The minimum transformer size that is required is
determined in the table below
Component Power kW
10hp Spindle Motor 7 50
X axis Motor 0 60
Y axis Motor 0 60
Z axis Motor 0 60
Flood Pump 0 75
Lube Pump 0 15
Total Power kW 10 20
Transformer kVA 12 75
If you need any more assistance in determining any kind of power related calculations there is a handy
power calculator at
http //dieselserviceandsupply com/power_calculator aspx
Doc ument History
Rev2 Created on 2012 08 29 by #270
Rev1 Created on 2004 08 26 by #000