Carbolite CDF 15/1b - Manual (Page 8)

CDF
8
MF56 – 1.03
4.5 Element Ageing
Silicon carbide elements gradually increase in resistance with use: a process known as ageing.
Their heating power reduces correspondingly.
If the furnace does not reach temperature, or is slow, the elements have aged to a high a resistance
and it may be necessary to replace them.
4.6 Power Adjustment
The furnace control system incorporates electronic power limiting. Power is supplied to the
elements in bursts of about 1/3rd second duration. This prevents overheating of the elements. The
power limit is compensated for, by the aid of the soft start function which will limit the initial
output power until a programmed temperature is reached, whereby the furnace can control the
ramp rate of the program without applying full power.