MRF
16/22
MF 55-GB 1.21
15
furnace, with consequent damage to both.
4.5
Thermocouples – low temperatures
At temperatures below 600°C the thermocouples will not give accurate readings. When the
furnace is started from cold they may show a negative temperature.
If the Setpoint temperature is at 0°C, this negative temperature reading will cause the heating
power to come on. To ensure that heating power does not come on when it is not required,
turn the Setpoint temperature down to -20°C. This will ensure that radiant heating power is not
applied when the furnace is not in use, after the end of a program or when using only the
microwave power.
This furnace is designed for operation over 800°C, it may be run below this temperature, but
accurate temperature measurement and stability are not assured.
4.6 Thermal
cut-outs
A self resetting thermal cut-out is located on the back of the magnetron.
A self resetting thermal cut-out, located in the element circuit transformer, cuts power if the
transformer core overheats.
If any of the thermal cut-outs are activated, then power to the elements and microwave is cut
and a red fault light on the control panel is illuminated.
