nVent RAYCHEM EM4-CW Manuel D'installation page 21

Problem B: residual current device trips
Probable causes
Excessive moisture in junction box
Earth fault at:
• connection
• damaged heating cable
Leakage current too high:
power cable or heating cable too long
Contactor bouncing
Voltage spikes in power supply network
Defective rcd
Problem C: Ice/snow not melting
Probable causes
Loss of supply current due to over-current
or residual current device operating.
Loss of supply cable continuity
Incorrect setting or operation of system
controls
Incorrect contactor sizing or damaged contactor
Problem D: Ice/snow begins to melt, but system turns off too soon
Probable causes
Incorrect setting or operation of system
controls.
Correction
Dry out and check seal; replace if necessary.
Perform an insulation resistance test.
Locate and rectify the fault and reset or
replace rcd.
Correct problem and re-design.
Replace with higher quality contactor
Reset rcd. If condition persists, use clean
power supply.
Replace
Correction
Follow procedures outlined in A and B above.
Locate and rectify fault.
Repair system controls or set system controls
correctly
Rectify
Correction
Repair system control unit or set system controls
correctly.
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