Siemens SIPROTEC 4 7UT6 Series Manual page 353

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The short-circuiters of the connectors for the current circuits have to be checked. This can be done using
secondary test equipment or other test equipment for checking continuity. Make sure that terminal
continuity is not wrongly simulated in reverse direction via current transformers or their short-circuiters.
– Remove the front panel.
– Remove the ribbon cable connected to the input/output module and pull the module out until there
is no contact between the module and the rear connections of the device.
7UT612: A-I/O-3 slot 19
7UT613: C-I/O-9 slot 33
7UT633: C-I/O-9 slot 33 right side
7UT635: C-I/O-9 slot 33 right side
– At the terminals of the device, check continuity for each pair of terminals that receives current from
the CTs.
– Firmly re-insert the I/O board.
– At the terminals of the device, again check continuity for each pair of terminals.
– Repeat the above continuity tests for the other boards that receive current from the CTs.
7UT613: C-I/O-2 slot 19
7UT633: C-I/O-2 slot 19 rechts
7UT635: C-I/O-9 slot 19 right
– Carefully plug in the ribbon cable. Be careful not to bend any connector pins. Do not apply force!
– Attach the front panel and tighten the screws
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Connect an ammeter in the supply circuit of the power supply. A range of about 2.5 A to 5 A for the
meter is appropriate.
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Switch on m.c.b. for auxiliary voltage (supply protection), check the voltage level and, if applicable, the
polarity of the voltage at the device terminals or at the connection modules.
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The measured steady-state current should correspond to the quiescent power consumption of the device.
Transient movement of the ammeter merely indicates the charging current of capacitors.
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Automat für die Versorgungs-Hilfsspannung ausschalten.
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Disconnect the ammeter; restore the normal power supply connections.
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Switch on voltage transformer protective breaker (if used).
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Verify that the voltage phase rotation at the device terminals is correct.
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Open the miniature circuit breakers for the transformer voltage (VT mcb) and the power supply.
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Check tripping circuits to the circuit breakers.
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Verify that the control wiring to and from other devices is correct.
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Check the signalling connections.
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Close the protective switches.
SIPROTEC 4, 7UT6x, Manual
C53000-G1176-C230-5, Edition 09.2016
Mounting and Commissioning
3.2 Checking Connections
353