EMC filters are generally fitted and these may give false results as they may be
designed to have a small leak to earth.
The insulation on heating elements generally has a small leakage particularly when
older.
With the oven / furnace isolated and disconnected from the mains:
Earth Continuity:
Measure from main incoming earth point to any accessible conducting panel, screw
head, frame member, controls mounting plate or earth connection point on any
electrical device.
Limit: Continuity to be < 0.5 ohm
Electrical Resistance (Safety)
Test by using a Mega Tester or similar and apply 500V DC between:
L & Earth and N & Earth
before and after the main contactor and any switching / isolating devices.
Limit: Resistance to be > 1M ohm
High Voltage Flash Testing
Do not perform this as the digital controllers and solid state switching devices may be
damaged.
PAT (Portable Appliance Testing) Testing
Small ovens and furnaces rated less than 3 kW fitted with a UK 13 Amp domestic plug
can be tested using this technique if the tester is set to “computer or electronically
sensitive equipment” mode. This is to protect the digital temperature controllers and
solid state switching devices fitted.
Any faults should be investigated and rectified as necessary.
7.4.21
Final Inspection and Testing
Ensure the product is switched off and cool. Run the product through a normal
operating cycle and confirm it heats up and cools down correctly as required by its
temperature controller.
7.4.22
Power Limiting Control
If an older product fails to achieve the normal operating temperature in the required
time, when it had originally not had this problem, it may be due to an age related
performance reduction in the heating elements.
It may be possible to compensate for this by increasing the power output setting in the
temperature controller’s parameter OP.Hi (if not already set to 100% - refer to power
rating section 11.0 for setting values).
Resetting this should only be done if all other obvious causes have been eliminated and
after consulting Carbolite as entering the wrong setting can cause damage.
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