750-211 (revised 2009)
Promethean Boilers, Model 4WI Manual
8-7
8.5 — Electrical Controls
Thermal relay units (overloads) are of the melting-alloy type and, when
tripped, the alloy must be given time to re-solidify before relay can be reset.
If the overloads trip out repeatedly when the motor current is normal,
replace them with new overloads. If the condition continues after replace-
ment, it will be necessary to determine the cause of excessive current draw
at the overloads.
Power supply to the boiler must be protected with dual element fuses
(Fusetrons®) or circuit breakers. Similar fuses should be used in branch
circuits. Standard one-shot fuses are not recommended. Information given
below is included for guidance to fuse requirements.
FIGURE 8-8. Entry Box
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