Figure 141
Withdrawable part with measurement unit
95.1
Voltage transformer
95.2
Resin tube (with fuse)
95.3
Fuse
90
7.3.2.5.2 Cleaning and checking of the voltage transformers and anti-ferroresonance circuit
a) Fixed version voltage transformers
• Make the plant you want to work on safe (follow the plant safety regulations);
• Make sure that the circuit-breaker is in the open position;
• Rack the circuit-breaker out from the service position to the test/isolated position;
• Remove the circuit-breaker from the panel;
• Manually close the earthing switch;
• Open the cable compartment door;
• Remove the circuit-breaker plate 27 to get larger access;
• Visually check the voltage transformer connections.;
• Using a dynamometric spanner check tightness of all the screws. Refer to the table on page 87 for
the tightening values;
• Carry out a visual inspection of the transformers and check for any presence of dirt;
• Remove any deposits of dust using a dry cloth that does not leave any deposits on the treated
surfaces (do not use woollen cloths).
b) Voltage transformers in removable version
• Make the plant you want to work on safe (follow the plant safety regulations);
• Make sure that the circuit-breaker is in the open position;
• Rack the circuit-breaker out from the service position to the test/isolated position;
• Manually close the earthing switch;
• Open the cable compartment door;
• Manually withdraw the VT truck (figure 17).
• Carry out a visual inspection of the transformers and check for any presence of dirt.
• Remove any deposits of dust using a dry cloth that does not leave any deposits on the treated
surfaces (do not use woollen cloths).
c) Voltage transformers in withdrawable version
• Make the plant you want to work on safe (follow the plant safety regulations);
• Make sure that the circuit-breaker is in the open position;
• Rack the circuit-breaker out from the service position to the test/isolated position;
• Open the cable compartment door;
• Manually withdraw the VT truck (figure 141);
• Carry out a visual inspection of the transformers and check for any presence of dirt;
• Remove any deposits of dust using a dry cloth that does not leave any deposits on the treated
surfaces (do not use woollen cloths).
95.2
95.3
95.1