4.17 Frequency Protection (ANSI 81)
431
7UM62 Manual
C53000-G1176-C149-3
4.17
Frequency Protection (ANSI 81)
Setting Ranges/
Resolutions
Number of Frequency Elements
4: each can be 81/O or 81/U
Pickup Frequency
f> or f<
40.00 Hz to 65.00 Hz (Increments 0.01 Hz)
(81–1 to 81–4)
Delay Time
T f1 (81–1)
0.00 s to 600.00 s
(Increments 0.01 s)
T f2 to T f4
0.00 s to 100.00 s
(Increments 0.01 s)
(81–2 to 81–4)
Undervoltage Blocking
10.0 V to 125.0 V
(Increments 0.1 V)
(U
1
Positive Sequence Voltage)
The set times are pure delay times.
Inherent Operating
Times
Pickup Times
f>, f<
Approx. 100 ms
81/O or 81/U
Dropout Times
T (f<, f<)
Approx. 100 ms
81/O or 81/U
Dropout Frequency
∆
f = | Pickup Value – Dropout Value |
Approx. 20 mHz
Dropout Voltage
Dropout Ratio for
Undervoltage Blocking
Approx. 1.05
Tolerances
– Pickup Frequencies
f>, f<
10 mHz (at U = U
N
; f = f
N
)
81/O or 81U
– Undervoltage Blocking
1 % of set value or 0.5 V
– Delay Times
T (f<, f<)
1 % of set value or 10 ms
81/O or 81/U
Influencing
Variables
Power Supply DC Voltage (U
DC
) in Range
0.8
≤
U
PS
/ U
PS nominal
≤
1.15
0.1 %
Temperature in Range
23 °F
≤ ϑ
amb
≤
131 °F
0.3 % / 10 °F
–5 °C
≤ ϑ
amb
≤
55 °C
0.5 % / 10 K
Harmonics
– Up to 10 % 3rd Harmonics
< 1 %
– Up to 10 % 5th Harmonics
< 1 %
