CRMagnetics Catalog

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89
Current Transformers
F
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Typical Applications
The actual current ratio may be changed from the name-
plate ratio by wrapping the primary and/or secondary
leads through the window opening.
ACTUAL
TURNS
RATIO
NAMEPLATE RATIO
NUMBER OF SECONDARY TURNS
THROUGH WINDOW OPENING
NUMBER OF PRIMARY TURNS
THROUGH WINDOW OPENING
=
±
125
5
3
11
2
—
=
TURNS RATIO = 11:1
CURRENT RATIO = 55:5
This illustration shows how a current transformer with a
nameplate turns ratio of 125:5 can be rescaled to oper-
ate as a non-standard 55:5 ratio transformer.
WHERE:
Nameplate ratio = 125 (125/5)
Number of secondary turns through window = - 3
Use -3 because the secondary wire is routed from X1 terminal
first
through the H1 side and out the H2 side
(Use + if the wire was routed first through the X2 side)
Number of primary turns through window = 2
- Wire from X1 terminal is routed through
the H1 side and out the H2 side
+ Wire from X1 terminal is routed through
the H2 and out the H1 side
PRIMARY
(55 AAC)
SECONDARY
(5 AAC)
Changing Current Transformer Ratios
Example