7PG2113/4/5/6 Solkor Description of Operation
4.1.3 Time Delayed Overcurrent Protection (51)
Two time delayed overcurrent elements are provided in the 7PG2113/5 relay and four elements are provided in
the 7PG2114/6 relay.
51-1, 51-2, (51-3 & 51-4 –7PG2114/6)
51-n Setting
sets the pick-up current level. Where the voltage controlled overcurrent function (51VCO) is used a
multiplier is applied to this setting where the voltage drops below the setting
VCO Setting
, see Section 3.2.
A number of shaped characteristics are provided. An inverse definite minimum time (IDMT) characteristic is
selected from IEC, ANSI or manufacturer specific curves using
51-n Char
. A time multiplier is applied to the
characteristic curves using the
51-n Time Mult
setting. Alternatively, a definite time lag delay (DTL) can be
chosen using
51-n Char
. When Definite Time Lag (DTL) is selected the time multiplier is not applied and the
51-n
Delay (DTL)
setting is used instead. The full list of operating curves is given in Section 2 – ‘Settings and
Instruments Guide’. Operating curve characteristics are illustrated in Section 3 – ‘Performance Specification’.
The
51-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
51-n Min. Operate Time
setting.
A fixed additional operate time can be added to the characteristic using
51-n Follower DTL
setting.
Where directional elements are present the direction of operation can be set using
51-n Dir. Control
setting.
Directional logic is provided independently for each 51-n element
Operation of the time delayed overcurrent elements can be inhibited from e.g. giving the option of using two
elements set to forward and two to reverse.
Inhibit 51-n
A binary or virtual input.
79 P/F Inst Trips: 51-n
When ‘delayed’ trips only are allowed in the auto-reclose sequence
(
79 P/F Prot’n Trip n
=
Delayed
).
51c
Activation
of
the cold load settings.
51-n Inrush Action: Block
Operation of the inrush current detector function.
51-n VTSAction: Inhibit
Operation of the VT Supervision function (7PG2114/6).
©2010 Siemens Protection Devices Limited Chapter 1 Page 38 of 80