Trip Circuit Supervision - For Details See Sections 2.10 And 3.8; Cold Load Protection - Siemens 7SG11 Manual

CT Failure
Current Setting
I
1 out of 3 < I
A
I
2 out of 3 < I
B
3 out of 3 = no-op
I
C
Figure 2.5-2
Table 2-15 Current Transformer Fail Settings
Sub-menu: Protection
Setting name
Gn CT Failure Setting
Gn CT Failure Delay
Sub-menu: O/P Relay Config.
Setting name
Gn CT Failure
2.5.4

Trip Circuit Supervision - for details see sections 2.10 and 3.8

2.6

Cold Load Protection

Argus 4 and Argus 6 only
A cold load protection function is provided to cater for closing onto the type of load that, after being de-energised
for some time, on energisation takes a high level of current for an extended period.
The System Config.:Cold Load Pickup Group setting allows the user to select the setting group number to which the
relay will switch after the circuit breaker has been open for longer than the user-set Auto-reclose:Cold Load Enable
time. This cold load group's overcurrent settings will normally be set higher and the time characteristics will be set
slower than the normally-active group's settings. The relay will switch to the nominated cold load group n and then
when the circuit breaker is closed will apply that group's overcurrent and auto-reclose settings until the user-set
Autoreclose:Cold Load Reset time expires, then revert to the normally-active group.
The Relay can be set up to revert to the normally active group sooner if the load current falls and remains below
the cold load group's Protection:P/F Highset 2 Setting for longer than the Protection:P/F Highset 2 Delay timer. Phase-fault
highset 2 in the set cold load group operates as an under-current element. This element's setting should be set,
5% or more, below the normally-active group's phase-fault overcurrent element settings. This prevents the relay
from changing back, from the cold load group to the normally active group, before the cold load inrush current has
fallen below the normally active group's P/F starter settings, so that when the relay reverts to the normally-active
group settings the relay does not then operate and give a trip output. The cold load group's phase-fault highset 2
element will be picked up during cold load inrush conditions and should not be user mapped to the trip relay.
Selecting the cold load group's Phase Fault highset 2 to OFF will de-select this fast revert mode, reversion will
then only occur at the end of the cold load reset delay.
At the end of the cold load reset delay, if the current is still above the HS2 setting, or any starter is picked up, the
relay will issue a trip and lockout. It will then revert to the normally-active group settings.
Automatic cold load pick-up can be disabled by setting the Auto-reclose:Cold Load Enable time delay to OFF. This still
allows Cold Load Group n to be selected via a mapped Status Input.
©2013 Siemens Protection Devices Limited
CT Failure Time Delay
CTF
CTF
Functional Diagram – Current Transformer Fail
Range (bold = default)
OFF, 0.05, 0.1 ... 1.00
OFF, 0.00, 0.01...20.00, 20.5
...100, 101 ... 300 s
Range (bold = default)
_, 1 for each output contact
(default: _ _ _ _ _ _ _ _ _ _ _ )
7SG11 Argus Technical Reference
CT Failure
Event CT Failure
P300008 Protection Functions / CTF
Units Notes
xIn
sec
Units Notes
P20007 Page 33 of 71