©2017 Nelson Heat Tracing Systems
GA2497 Rev.5
10
The Soft-Start feature enables self-regulating cables to be
energized at low temperatures without causing excessive load
on the electrical system and extending cable life by reducing
cable internal heating due to inrush currents. The
resistance
of self-regulating cables decreases as the cables get
colder, which results in higher current and can result in
breaker trips if temperatures are very cold and the
installed length of cable is long. The Soft-Start feature
operates by initially only energizing the cable for a very short
period of time – while the current draw may be high during
this period, the period is usually short enough to reduce
average load on the electrical system.
5.9 Soft-Start Feature
This short energization period is repeated and eventually
increased; after a few minutes, the cable is usually warm
enough
such that the resistance has increased and the
current decreased to the point where it can be continuously
energized.
CM-2201/CM-2202
General Operation
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