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Mounting and Commissioning
3.2 Checking Connections
• The short-circuit feature of the current circuits of the device is to be checked. This may be performed with
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 circuit links.
– Remove the front cover of the device (see also Figure 3-3 and 3-4).
– Remove the ribbon cable connected to the C–I/O-2 board and pull the board out until there is no contact
between the board and the rear connections of the device.
– 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 module. Carefully connect the ribbon cable. Be careful not to bend connecting
pins! Do not apply force!
– At the terminals of the device, again check continuity for each pair of terminals that receives current from
the CTs.
– Attach the front panel and tighten the screws.
• 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.
• Switch on mcb 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.
• 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.
• Remove the voltage from the power supply by opening the mcb.
• Disconnect the measuring equipment; restore the normal power supply connections.
• Apply voltage to the power supply.
• Close the mcb for the voltage transformers.
• Verify that the voltage phase rotation at the device terminals is correct.
• Open the mcb's for the transformer voltage (VT mcb) and the power supply.
• Check the trip circuits to the power system circuit breakers.
• Check the close circuits to the power system circuit breakers.
• Verify that the control wiring to and from other devices is correct.
• Check the signalling connections.
• Close the protective switches.
• If communication converters are used: check the auxiliary voltages for the communication converters.
• If the communication converter is connected to the communication network, its device-ready relay (DOK =
„Device Ok") picks up. This also signalizes that the clock pulse of the communication network is recognized.
Further checks are performed according to Section „Checking the Protection Data Topology".
• You must also observe the documentation supplied with the communication converters.
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SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
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