Repairs; Switchgear In General - ABB UniGear ZS1 Instruction Manual

7.4 Repairs

7.3.4.3 Measuring the insulation resistance of the auxiliary circuits
• 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 circuit-breakers 25 positioned inside the low voltage compartment to remove the auxiliary
power supply to the panel;
• From one of the circuit-breakers 25 disconnect the wires on the internal side of the panel, short-circuit
the man apply 500 Vcc;
• Using the Megger instrument, measure the resistance between the phase involved and the
conductive electric part (switchgear structure). The value must not be less than 2MΩ and in any case
constant over time;
• Repeat the operation for the number of circuits (circuit-breakers) inside of the panel (110Vdc,
220Vac, etc).
• Replace the connections and put the panel into service.

7.4.1 Switchgear in general

Repair of surface damage:
• Carry out repair work immediately after a defect has been discovered;
• Completely remove all rust from damaged paintwork areas on steel sheet and other steel parts by
mechanical means, e.g. with a wire brush;
• Lightly grind the surrounding paint coat and carefully degrease the entire area. Then immediately
apply an anti-rust primer and, after an appropriate hardening time, apply the top coat. Only use
suitable and compatible paint products;
• Apply the top coat in standard RAL 7035 colour, or the relevant special colour;
• Carefully remove any white rust on aluminium/zinc surfaces with a wire brush or cleaning pad, e.g.
Scotch-Brite, and clean loosely adhering particles with a dry, non-fraying cloth. Next treat the
cleaned parts with zinc spray or zinc powder paint and, finally, treat with aluminium spray for colour
matching;
• Carefully remove any white rust from passivated operating parts and rust formation on phosphatised
parts with a wire brush or metal-free cleaning pad, e.g. Scotch-Brite, and clean with a dry cloth. Then
grease evenly (with mechanical grease for moving parts).
Apparatus in general:
• Follow the maintenance instructions in the manuals for individual equipment components;
• Check that the bolt connections at the contact points in the busbar system and the earth connections
are tight, and that the contact system functions correctly;
• Where necessary, grease slide plates and bearings in the panel again or thoroughly clean them.
Then grease them again with mechanical grease for moving parts lubricant;
• Top up grease on contact areas in the contact system when corroded or otherwise as necessary,
or, when lubrication is inadequate or missing, thoroughly clean the areas concerned and grease
them again with mechanical grease for moving parts lubricant;
• Remove the contact system for thorough cleaning as described below (Figures 7/1, 7/3):
- Slide in the two inner ring tension springs 4.4 facing the breaker pole to a position beside the other
two outer ring tension springs, thus releasing contact system 4.3, and remove the contact system;
- The contact pin of the contact system and the slot on the contact arm must be cleaned and greased.
Fit contact system back to front on the thin end of arbor 127 and slide it forwards onto the thicker
part of the shank;
- Fit arbor 127 onto the relative contact arm 4.2, slide the contact system 4.3 over onto the contact
arm, and withdraw the arbor;
- Check that all contact fingers and ring tension springs have a perfect fit.
Replacement of the contact pins when the surface is damaged
After any required replacement of contact pins 4.1 (figure 147), the latter should be retightened using
the socket head bolts.
Thread Rated tightening torque ungreased
M10
M20
46 Nm
250 Nm
93