MSCDN – MP2A Performance Specification
4.5 R1/2 49 Resistor Thermal Overload
Thermal overload element applied to each phase of each resistor independently.
Accuracy
Pickup
100% of setting ± 5% or ± 0.02 I
n
Reset
≥
95% of I
s
Repeatability ±
2%
Operate Time
± 5% or ± 0.1s
Frequency Range
1
st
, 2
nd
…15
th
Harmonic
Operating Time
Characteristic Ranges
THERMAL
IEC 60255-8
Operate times are calculated from:
(
)
⎭
⎬
⎫
⎩
⎨
⎧
×
−
−
×
τ
=
2
2
2
P
2
I
I
I
ln
B
I
k
t
τ
= thermal time constant
I = measured current
I
P
= prior current
I
B
= basic current
k = constant
τ
Factor
1 to 10000
Δ
0.5 seconds
4.6 50 Resistor Open Circuit
An instantaneous/delayed overcurrent element measures the difference in currents on each resistor on a phase-by-
phase basis.
Accuracy
Pickup
100% of setting ± 5% or ± 0.02 I
n
Reset
≥
95% of I
s
Repeatability ±
2%
Operate Time
± 1% or ± 10ms
Operating Time
Current Applied
Typical
2 x setting
2 cycles
4 x setting
1.5 cycle
4.7 49 Reactor Thermal Overload
Thermal overload element applied to each phase of the reactor independently.
Accuracy
Pickup
100% of setting ± 5% or ± 0.02 I
n
Reset
≥
95% of I
s
Repeatability ±
2%
Operate Time
± 5%
Frequency Range
1
st
, 2
nd
…15
th
Harmonic
Operating Time
Characteristic Ranges
THERMAL
IEC 60255-8
Operate times are calculated from:
(
)
⎭
⎬
⎫
⎩
⎨
⎧
×
−
−
×
τ
=
2
2
2
P
2
I
I
I
ln
B
I
k
t
τ
= thermal time constant
I = measured current
I
P
= prior current
I
B
= basic current
k = constant
τ
Factor
1 to 1000
Δ
0.5 minutes
4.8 50 Backup Overcurrent
Three phase definite time overcurrent element.
©2011 Siemens Protection Devices Limited
Chapter 2 Page 9 of 13
