15.3 Repair instruction
Never disconnect the secondary connection of a 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.
Never connect or disconnect a wire and/or a connector to or from a IED
during normal service. Hazardous voltages and currents are present that
may be lethal. Operation may be disrupted and IED and measuring
circuitry may be damaged.
An alternative is to open the IED 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 replacement modules.
Strictly follow the company and country safety regulations.
Most electronic components are sensitive to electrostatic discharge and latent damage
may occur. 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
ground.
Disassemble and reassemble the IED accordingly:
1. Switch off the dc supply.
2. Short-circuit the current transformers and disconnect all current and voltage
connections from the IED.
3. Disconnect all signal wires by removing the female connectors.
4. Disconnect the optical fibers.
5. Unscrew the main back plate of the IED.
6. If the transformer module is to be changed:
• Remove the IED from the panel if necessary.
• Remove the rear plate of the IED.
• Remove the front plate.
• Remove the screws of the transformer input module, both front and rear.
7. Pull out the faulty module.
1MRK 504 165-UUS - Section 15
Troubleshooting
Transformer protection RET670 2.2 ANSI 309
Commissioning manual
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