Protection functions
Table 29. Three-phase non-directional overcurrent protection (PHxPTOC)
Characteristic
Value
Operation accuracy
Depending on the frequency of the current measured: f
n
±2 Hz
PHLPTOC
±1.5% of the set value or ±0.002 x I
n
PHHPTOC
and
PHIPTOC
±1.5% of set value or ±0.002 x I
n
(at currents in the range of 0.1…10 x I
n
)
±5.0% of the set value
(at currents in the range of 10…40 x I
n
)
Start time
1)2)
Minimum
Typical
Maximum
PHIPTOC:
I
Fault
= 2 x set
Start value
I
Fault
= 10 x set
Start value
16 ms
11 ms
19 ms
12 ms
23 ms
14 ms
PHHPTOC and PHLPTOC:
I
Fault
= 2 x set
Start value
22 ms
24 ms
25 ms
Reset time
< 40 ms
Reset ratio
Typical 0.96
Retardation time
< 30 ms
Operate time accuracy in definite time mode
±1.0% of the set value or ±20 ms
Operate time accuracy in inverse time mode
±5.0% of the theoretical value or ±20 ms
3)
Suppression of harmonics
RMS: No suppression
DFT: -50 dB at f = n x f
n
, where n = 2, 3, 4, 5,…
Peak-to-Peak: No suppression
P-to-P+backup: No suppression
1)
Set
Operate delay time = 0,02 s, Operate curve type = IEC definite time, Measurement mode = default (depends on stage), current before fault = 0.0 x In, fn = 50 Hz, fault current in one
phase with nominal frequency injected from random phase angle, results based on statistical distribution of 1000 measurements
2)
Includes the delay of the signal output contact
3)
Includes the delay of the heavy-duty output contact
Transformer Protection and Control
1MRS757846 A
RET620
Product version: 2.0
26
ABB
