Specification
Page 11 of 94 057-236 ISSUE: 1
2.7.1 VA RATING OF THE CTS
NOTE: Details for 4 mm² cables are shown for reference only. The connectors on the DSE
modules are only suitable for cables up to 2.5 mm².
The VA burden of the module on the CTs is 0.5 VA. However depending upon the type and length of
cabling between the CTs and the module, CTs with a greater VA rating than the module are required.
The distance between the CTs and the
measuring module should be
estimated and cross-referenced
against the chart opposite to find the
VA burden of the cable itself.
If the CTs are fitted within the
alternator top box, the star point
(common) of the CTs should be
connected to system ground (earth) as
close as possible to the CTs. This
minimises the length of cable used to
connect the CTs to the DSE module.
Example.
If 1.5 mm² cable is used and the
distance
from the CT to the measuring
module is 20 m, then the burden of the
cable alone is approximately 15 VA.
As the burden of the DSE controller is
0.5 VA, then a CT with a rating of at
least 15 VA + 0.5 VA = 15.5 VA must
be used.
If 2.5 mm² cables are used over the
same distance of 20 m, then the
burden of the cable on the CT is
approximately 7 VA. CT’s required in
this instance is at least 7.5 VA (7 +
0.5).
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