7PG2113/4/5/6 Solkor Description of Operation
Figure 4.2-2 Logic Diagram: Derived Instantaneous Earth Fault Element
4.2.3 Time Delayed Derived Earth Fault Protection (51N)
Two time delayed derived earth fault elements are provided in the 7PG2113/5 relay and four elements are
provided in the 7PG2114/6 relay.
51N-1, 51N-2, (51N-3 & 51N-4 – 7PG2114/6)
51N-n Setting
sets the pick-up current level.
A number of shaped characteristics are provided. An inverse definite minimum time (IDMT) characteristic is
selected from IEC and ANSI curves using
51N-n Char
. A time multiplier is applied to the characteristic curves
using the
51N-n Time Mult
setting. Alternatively, a definite time lag delay (DTL) can be chosen using
51N-n
Char
. When definite time lag (DTL) is selected the time multiplier is not applied and the
51N-n Delay (DTL)
setting is used instead.
The
51N-n Reset
setting can apply a
definite time delayed
reset
,
or when configured as an ANSI characteristic
an
ANSI (DECAYING)
reset. If ANSI (DECAYING) reset is selected for an IEC characteristic, the reset will be
instantaneous. The reset mode is significant where the characteristic has reset before issuing a trip output – see
‘Applications Guide’.
A minimum operate time for the characteristic can be set using the
51N-n Min. Operate Time
setting.
A fixed additional operate time can be added to the characteristic using the
51N-n Follower DTL
setting.
Where directional elements are present the direction of operation can be set using
51N-n Dir. Control
setting.
Directional logic is provided independently for each 51N-n element.
Operation of the time delayed earth fault elements can be inhibited from:
Inhibit 51N-n
A binary or virtual input.
79 E/F Inst Trips: 51N-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.
51N-n VTSAction: Inhibit
Operation of the VT Supervision function (7PG2114/6).
©2010 Siemens Protection Devices Limited Chapter 1 Page 43 of 80