7SR210 & 7SR220 Description of Operation
Unrestricted Page 28 of 94
©2018 Siemens Protection Devices Limited
3.1.3
Time Delayed Overcurrent Protection (51)
Two time delayed overcurrent elements are provided in the 7SR21 relay. Four elements are provided in the
7SR22 relay e.g. giving the option of using two elements set to forward and two to reverse.
51-n Setting
sets the pick-up current level. Where the voltage controlled overcurrent function (51VCO) is used
(7SR22 relays only) 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 and ANSI 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
Delay (DTL) is selected the time multiplier is not applied and the
51-n Delay (DTL)
setting is used instead.
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: -
Inhibit 51-n
A binary input, virtual input, function key or remote data Comms
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 (see section 3.7).
51-n Inrush Action:
Inhibit
Operation of the inrush current detector function.
51-n VTSAction:
Inhibit
Operation of the VT Supervision function (7SR22).
Summary of Contents for Argus 7SR21
Page 1: ...Energy Management 7SR21 7SR22 Argus Overcurrent Relay Reyrolle Protection Devices ...
Page 2: ......
Page 4: ...Contents 7SR11 and 7SR12 Page 2 of 2 2018 Siemens Protection Devices Limited ...
Page 185: ...7SR210 Settings Guide Unrestricted 2018 Siemens Protection Devices Limited Page 61 of 61 ...
Page 277: ...7SR220 Settings Guide Unrestricted Page 72 of 107 2013 Siemens Protection Devices Limited ...
Page 382: ...7SR220 Technical Manual Chapter 4 Page 2 of 96 2017 Siemens Protection Devices Limited ...
Page 386: ...7SR220 Technical Manual Chapter 4 Page 6 of 96 2017 Siemens Protection Devices Limited ...
Page 398: ...7SR220 Technical Manual Chapter 4 Page 18 of 96 2017 Siemens Protection Devices Limited ...
Page 414: ...7SR220 Technical Manual Chapter 4 Page 34 of 96 2017 Siemens Protection Devices Limited ...
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