Crompton Controls M10 - Manual (Page 13)

Emotron AB 01-2550-01r3 Selecting the current transformer 11
6 Selecting the current transformer
6.1 For motors up to 50 A
1. Check the rated motor current on the motor plate.
2. Compare this value with the rated motor current in Table 1.
3. From Table 1, select the current transformer and the appropriate numbers of
windings.
6.1.1 Example
Rated motor current = 12 A.
• Select 10.1 - 12.5 A from the first column in table 1 and choose CTM 025
with two (2) primary windings (the motor wire is drawn through the CTM
hole twice).
In order to ensure an accurate calibration of the Emotron M10, it is essential
that you use the correct CTM and apply the exact number of windings in
accordance with the above table.
Table 1 Current transformer and number of primary windings.
RATED MOTOR CURRENT (A)
Number of primary windings
CTM010 CTM025 CTM050
0.4 - 1.0 10
1.01 - 2.0 5
2.01 - 3.0 3
3.1 - 5.0 2
5.1 - 10.0 1
10.1 - 12.5 2
12.6 - 25 1
26 - 50A 1
NOTE: Max. length of CTM cable is 1 m (39 inches). For motors with rated
current over 50 A Emotron M20 must be used, contact your supplier.