9.3 Protection stages
9 Technical data
Technical description
198
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VM59.EN001
9.3.2.
Overcurrent protection
Overcurrent stage I> (50/51)
Pick-up current
0.10 – 5.00 x I
MODE
Definite time function:
DT
- Operating time
0.08
**)
– 300.00 s (step 0.02 s)
IDMT function:
- Delay curve family
(DT), IEC, IEEE, RI Prg
- Curve type
EI, VI, NI, LTI, MI…depends on the family *)
- Time multiplier k
0.05
20.0, except
0.50
20.0 for RXIDG, IEEE and IEEE2
Start time
Typically 60 ms
Reset time
<95 ms
Reset ratio
0.97
Inaccuracy:
- Starting
±3% of the set value or 5 mA secondary
- Operating time at definite time function
±1% or ±30 ms
- Operating time at IDMT function
±5% or at least ±30 ms (I< 50 x I
MODE
)
*) EI = Extremely Inverse, NI = Normal Inverse, VI = Very Inverse, LTI = Long Time Inverse
MI= Moderately Inverse
**) This is the instantaneous time i.e. the minimum total operational time including the fault
detection time and operation time of the trip contacts.
Overcurrent stages I>> and I>>> (50/51)
Pick-up current
0.10 – 20.00 x I
N
(I>>)
0.10 – 40.00 x I
N
(I>>>)
Definite time function:
- Operating time
DT
- I>>
0.04
**)
– 1800.00 s (step 0.01 s)
- I>>>
0.04
**)
– 300.00 s (step 0.01 s)
Start time
Typically 60 ms
Reset time
<95 ms
Reset ratio
0.97
Inaccuracy:
- Starting
±3% of the set value or 5 mA secondary
- Operation time
±1% or ±25 ms
**) This is the instantaneous time i.e. the minimum total operational time including the fault
detection time and operation time of the trip contacts.
Thermal overload stage T> (49)
Overload factor:
0.5 – 1.20 xI
MOT
(step 0.01)
Alarm setting range:
60 – 99 % (step 1%)
Time constant Tau:
2 – 60 min (step 1)
Cooling time coefficient:
1.0 – 5.0 xTau (step 0.1)
Max. overload at +40
C
70 – 120 %I
MOT
(step 1)
Max. overload at +70
C
50 – 100 %I
MOT
(step 1)
Ambient temperature
-55 – 125
C (step 1
Resetting ratio
0.95
Accuracy:
- operating time
±5% or ±1 s
