7PG2113/4/5/6 Solkor Description of Operation
Minimum Polarising Voltage
The
67N Minimum Voltage
setting defines the minimum polarising voltage level. Where the measured polarising
voltage is below this level no directional output is given and operation of protection elements set as directional will
be inhibited. This prevents mal-operation under fuse failure/MCB tripped conditions where noise voltages can be
present.
Figure 4.2-1 Logic Diagram: Derived Directional Earth Fault Element
4.2.2 Instantaneous Derived Earth Fault Protection (50N)
Two instantaneous derived earth fault elements are provided in the 7PG2113/5 relay and four elements are
provided in the 7PG2114/6 relay.
50N-1, 50N-2, (50N-3 & 50N-4 – 7PG2114/6)
Each instantaneous element has independent settings for pick-up current
50N-n Setting
and a follower time
delay
50N-n Delay
. The instantaneous elements have transient free operation.
Where directional elements are present the direction of operation can be set using
50N-n Dir. Control
setting.
Directional logic is provided independently for each 50-n element.
Operation of the instantaneous earth fault elements can be inhibited from:
Inhibit 50N-n
A binary or virtual input.
79 E/F Inst Trips: 50N-n
When ‘delayed’ trips only are allowed in the auto-reclose sequence
(
79 E/F Prot’n Trip n
=
Delayed
).
50-n Inrush Action: Block
Operation of the inrush current detector function.
50N-n VTSAction: Inhibit
Operation of the VT Supervision function (7PG2114/6).
©2010 Siemens Protection Devices Limited Chapter 1 Page 42 of 80