Carbolite CFM Series - Manual (Page 8)

CFM
8
MF10 - 3.08
All models. Occasionally the power limit is set to zero to permit demonstration of the controls
without the heating elements taking power. The operator may reset it to its standard value or the
value that it had before setting to zero.
4.6 Element Aging
Applicable to 1400°C models.
Silicon carbide elements gradually increase in resistance with use: a process known as aging. Their
heating power reduces correspondingly. To ensure sufficient power to the furnace it may be
necessary to adjust the power limit, and, ultimately, to replace the elements - taking care to
readjust the power limit.
If the furnace does not reach temperature, or is slow, measure the element resistances and calculate
the required power limit using the method given above. If it exceeds 100%, the elements have too
high a resistance and need replacing: check your data and calculations with Carbolite.
See the separate manual supplied for how to adjust the controller. Always record the setting when
first making an adjustment. If new elements are fitted, return the adjustments to the original value,
or remeasure and recalculate. A table of standard power limits in given is section 7.6.
CFM 14/4: This model has only a small margin for power limit adjustment on 240V. Power limit
adjustment should not be necessary.