Siemens 7SR12 Argus - Under;Over Frequency (81)

7SR11 & 7SR12 Commissioning and Maintenance Guide
©2017 Siemens Protection Devices Limited Chapter 6 Page 52 of 72
2.15 Under/Over Frequency (81)
7SR
12
46
BC
46
NPS
(x
2
)
37
(
x2
)
49
50
BF
51
V
V
L
1
(V
A
)
V
L
2
(
V
B
)
V
L
3
(V
C
)
I
L
1
(
I
A
)
81
HBL
2
37
(x
2)
49
50
BF
51
V
I
L
2
(
I
B
)
81
HBL
2
37
(
x2
)
49
50
BF
51
V
I
L
3
(
I
C
)
81
HBL
2
I
4
(
I
G
)
74
T
/
CCS
NOTE
:
The use of some
functions are mutually exclusive
67
/
50
(
x
4)
67
/
51
(x
4)
67
/
50
N
(x
4
)
67/
50
(x
4)
67
/
50
(x
4
)
67
/
51
(
x
4)
67/
51
(x
4)
67
/
51
N
(x
4)
67
/
50
SEF
67
/
51
SEF
27
59
(
x
4)
27
59
(
x4
)
27
59
(x
4)
47
(x
2)
79
Optional
59N
(
x2
)
Note
:
Example shows
Voltage Config
=
Van,
Vbn
, Vcn
60
CTS
60
VTS
50
BF
51
c
51
c
51
c
64
H
81
(
x4
)
Figure 2-18 Under/Over Frequency
Voltage Inputs: V
L1
(V
A
), V
L2
(V
B
), V
L3
(V
C
)
Current Inputs: n/a apply zero current to stabilize other functions
Disable:
Map Pickup LED: 81-n - Self Reset
This function can be tested by application of 1P or 3P voltage. For Over-frequency, the elements with the highest
setting should be tested first and for Under-frequency the elements with the lowest settings should be tested first.
The elements with other settings can then be tested without need to disable the elements already tested. Note
that the relay is designed to track the gradual changes in power system frequency and that sudden step changes
in frequency during testing do not reflect normal system operation. Normal ‘instantaneous’ operation of the
frequency element is 140-175ms in line with the Performance Specification. Application of sudden step changes
to frequency can add additional delay which can produce misleading test results.
Gradually increase/decrease applied voltage frequency until 81-n operation occurs. Elements set for more
extreme frequency fluctuation should be tested first with lesser elements disabled.
If the 81-n Delay setting is long it will be advantageous to map the function to temporarily drive the relevant
Pickup output in the Pickup Config sub-menu in the Output Config menu as this will allow the Pick-up led to
operate for the function. If the delay setting is short the operation of the element can be easily checked directly.
The frequency should then be gradually decreased/increased until the element resets. The reset frequency can
be used to check the Hysteresis setting.
If the element is set as 81-n U/V Guarded, The applied voltage must be above the 81 UV Guard Setting in the
U/O Frequency menu.
Apply setting frequency +0.5Hz for Over-frequency or -0.5Hz for Under-frequency and record operating time.
Starting with the element in the operated condition, gradually increase or decrease the applied voltage until the
element resets. Measure the reset voltage level to check the 81 Hysteresis setting.