Reed system of separation the busbar


The system is designed to disconnect the VDC busbar (traction) of voltage measurement circuits PBLDC (see page No. 109) and the measurement post insulator. During the operational test of substations supplying the traction, there is the possibility to perform the tests for ground faults.

Because of the way the interlocking relay PBLDC and the post measuring insulators work, between the busbar and the weight there is resistance turn on, which causes the false results during the tests for ground faults.

Reed system of separation the busbar allows to disconnect the busbar from measuring systems during the tests. How to connect the system is shown in Picture 1.

Connecting the reed system


To disconnect the busbar from the measurement systems the reed relay of high voltage with contacts normally closed (NC) is used. In the absence of the voltage on the operating coil, the system is in the ‘work’ position. The voltage from the busbar is applied on measiring post insulator by the compact reed contact and then to the PBLDC, which controlls the voltage on the busbar.

24 VDC in the coil results in disconnecting the contact of the reed and changing the position the system to ‘test’.  In this position, the measurement of earth fault is not vitiated by an error resulting from the resistance of the insulator and the PBLDC. 24VDC voltage is achieved by switching power inverter 230VAC - 24VDC. The change of state “work - test,” or opposite should be carried out in the absence of voltage on the busbar.

The use of high voltage reed relay allows the use of high voltage during the tests.

Technical data:

reed relay’s coil power supply 24 VDC
current consumed by the relay’s coil 80 mA
withstand voltage obtuse relay contacts 17 kVDC

The set includes:

  • high voltage reed (24 VDC coil)
  • converter 230 VAC – 24 VDC
  • post signaling insulator (adapted to work with reed)
  • interlocking relay PBLDC

Technical drawings:

Reed ralay
Post measuring insulator

All technical data presented in the catalog can be changed due to technological progress.


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