Check - MTU 20V4000G44F Operating Instructions Manual

8.14.9 Electrical operation of heating elements – Check
DANGER
Electrical voltage at exposed terminals and components.
Risk of serious injury - danger to life!
• Work must be carried out by trained, qualified and approved according to the regional regulations
personnel only!
• Ensure that no other persons have access to exposed terminals and/or components!
• Close terminal boxes and/or components immediately after completion of work!
• Act with extreme caution!
Checking electrical operation of heating elements
1. Check the electrical operation of the screw-in heating elements on the copper terminal in the housing.
2. Check the electrical conductivity between the phases of each individual output stage.
Result: The ohmic value must be balanced.
3. For the insulation check, apply 500 V direct voltage between the phases and the grounding.
Result: The insulating resistance should not be more than 10 MΩ.
4. For the dielectric strength test, apply a 2000 V alternating voltage for 1 minute between the phases and the
grounding.
5. If not all tests are positive:
1. Open protective cover of screw-in heating elements and check the integrity of the electrical connections.
2. Disconnect the feed cables to the screw-in heating elements.
3. Carry out tests in accordance with (→ Step 1) and (→ Step 2) between the feed cables to check the integ-
rity.
4. Carry out tests in accordance with (→ Step 1) and (→ Step 2) on the individual heating elements within
the protective cover.
5. Disconnect defective heating elements and replace them.
6. Assemble all disconnected parts again and visually check gaskets for leaks.
178 | Coolant Circuit, General, High-Temperature Circuit | MS15058/01E 2017-05