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2
Repair instruction
Repair instruction
Warning!
Never disconnect a secondary connection of current transformer circuit without short-circuiting
the transformer's secondary winding. Operating a current transformer with the secondary
winding open will cause a massive potential build-up that may damage the transformer and may
cause injuries to humans.
Warning!
Never connect or disconnect a wire and/or a connector to or from a terminal during normal ser-
vice. Hazardous voltages and currents are present that may be lethal. Operation may be disrupt-
ed and terminal and measuring circuitry may be damaged.
An alternative is to open the terminal and send only the faulty circuit board to ABB for repair.
When a printed circuit board is sent to ABB, it must always be placed in a metallic, ESD-proof,
protection bag. The user can also purchase separate modules for replacement.
Note!
Strictly follow the company and country safety regulations.
Caution!
Always use a conductive wrist strap connected to protective earth when replacing modules.
Electrostatic discharge (ESD) may damage the module and terminal circuitry.
Most electronic components are sensitive to electrostatic discharge and latent damage may oc-
cur. Please observe usual procedures for handling electronics and also use an ESD wrist strap.
A semi-conducting layer must be placed on the workbench and connected to earth.
Disassemble and reassemble the REx 5xx terminal accordingly:
1. Switch off the dc supply.
2. Short-circuit the current transformers and disconnect all current and voltage con-
nections from the terminal.
3. Disconnect all signal wires by removing the female connectors.
4. Disconnect the optical fibres.
5. Unscrew the main back plate of the terminal.
6. If the transformer module is to be changed — unscrew the small back plate of the
terminal.
7. Pull out the faulty module.
8. Check that the new module has correct identity number.
Chapter 16
Fault tracing and repair
171
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