PBL - interlocking relay


Interlocking relay (PBL) is designed for permanent and safe control of voltage presence on busbars in medium voltage switchgear. Voltage control prevents accidental grounding of the busbar. The relay is designed for operating with insulators equipped with capacitive or resistive dividers. The ralay can supply the coin, which blocks the connection of the earthing with the current, preventing the closing of the earthing switch in the presence of voltage at its terminals. The relay continuously measures the currents in the circuits of the three inputs (L1-N1, L2, N2, N3, L3) connected to the output of the measuring insulators. Switching relay: authorization is only in the absence of currents in the input circuits (currents below the threshold). Input circuit clamps are located on the rear panel. For proper operation of the relay you need auxiliary voltage supply to be connected to the clamps on the rear panel (L +, N-). 

The front panel includes banana type jacks connected directly to the input clamps on the rear panel. Next slots are independent from the auxiliary voltage signals, indicating the presence of current in the circuit inputs. On the left side the front panel, there are two control signals – red - no authorization signaling the flow of current in the circuit inputs and green - the authorization - signaling the lack of current flow. The controls are a direct representation of the position of the relay contacts. In the presence of voltage on the lines (L1-3) contacts are in a “no authorization” (compact P2-P3 and P4-P5, the relay in idle mode). In the absence voltage on the lines of contacts go into a state of “authorization” (shorted contacts P1-P2 and P4-P5, the relay energized).

PBL basic version:

  • executive element: P- 250 VAC, 24 VDC, 8A, 2P relay
  • input sensitivity: 60 µA- semi sensitive
  • auxiliary power supply: AC- 115/230 VAC, DC- 115/230 VDC, AC2- 24/12 VAC, DC2- 24 VDC
  • authorization: 1F- reaction for one or few poles, 3F – reaction for 3 poles at the same time

Technical drawings:

ELTOM reserves the right to make changes resulting from technological progress.




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