Micom P721, Technical Manual

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Commissioning and Maintenance P72x/EN CM/C21
MiCOM P721/P723 Page 5/28
3. PRODUCT VERIFICATION TESTS
BEFORE CARRYING OUT ANY WORK ON THE EQUIPMENT, THE
USER SHOULD BE FAMILIAR WITH THE CONTENTS OF THE SAFETY
GUIDE SFTY/4LM/E11 OR LATER ISSUE, OR THE SAFETY AND
TECHNICAL DATA SECTIONS OF THE TECHNICAL MANUAL AND
ALSO THE RATINGS ON THE EQUIPMENT RATING LABEL.
3.1 Allocation of terminals
Consult the appropriate wiring diagrams in the Connection Diagrams (CO) chapter while
observing the various polarities and ground/earth connections.
3.2 Electrostatic discharge (ESD)
The case of the P72x protects it from electrostatic discharge. Do not remove the front panel
unnecessarily.
A person’s normal movements can generate high electrostatic voltages which can cause
serious damage to electronic components. The damage is not always immediately apparent
but can reduce reliability.
For further details see the chapter Handling Installation and Case Dimensions (IN).
3.3 Visual inspection
Carefully examine the relay to see if there has been any possible deterioration following
installation.
Check the external wiring corresponds to the appropriate relay diagram or the assembly
diagram. The reference number of the relay diagram is on a label under the upper flap of the
front panel.
When the relay is withdrawn from its case, use a continuity tester to check if the current
short-circuits (phases and earth CTs) between the terminals indicated on the wiring diagram
are closed.
3.4 Earthing
Check if the earth connection of the case situated above the rear terminal block is used to
connect the relay to a local earth bar. With several relays present, make sure that the copper
earth bar is properly installed for solidly connecting the earthing terminals of each case.
3.5 Current transformers (CTs)
WARNING: NEVER OPEN CIRCUIT THE SECONDARY CIRCUIT OF A CURRENT
TRANSFORMER SINCE THE HIGH VOLTAGE PRODUCED MAY BE
LETHAL AND COULD DAMAGE INSULATION.