Micom ALSTOM P341, Technical Data Sheet

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P341 Technical Data Sheet
26
P341 Software versions 36 & 71J
The IEEE/US IDMT curves conform to the
following formula:
t = TD x
⎝⎜
⎜⎛
⎠⎟
⎟⎞
K
(
Ι
/
Ι
s)
α
- 1
+ L
Where:
t = Operation
time
K = Constant
Ι
= Measured current
Ι
S = Current threshold setting
α
= Constant
L = ANSI/IEEE constant (zero for
IEC/UK curves)
T = Time multiplier setting for
IEC/UK curves
TD = Time dial setting for IEEE/US
curves
IDMT characteristics
IDMT curve Stand. K
α
L
Standard
inverse
IEC 0.14 0.02 0
Very inverse IEC 13.5 1 0
Extremely
inverse
IEC 80 2 0
Long time
inverse
UK 120 1 0
Rectifier UK 45900 5.6 0
Moderately
inverse
IEEE 0.0515 0.02 0.114
Very inverse IEEE 19.61 2 0.491
Extremely
inverse
IEEE 28.2 2 0.1217
Inverse US-C08 5.95 2 0.18
Short time
inverse
US-C02 0.16758 0.02 0.11858
The IEC extremely inverse curve becomes
definite time at currents greater than 20 x
setting. The IEC standard, very and long time
inverse curves become definite time at
currents greater than 30 x setting.
For all IEC/UK curves, the reset characteristic
is definite time only.
For all IEEE/US curves, the reset characteristic
can be selected as either inverse curve or
definite time.
The inverse reset characteristics are
dependent upon the selected IEEE/US IDMT
curve as shown in the table below.
All inverse reset curves conform to the
following formula:
tRESET =
TD x S
(1 - M2)
in seconds
Where:
TD
= Time dial setting for IEEE
curves
S = Constant
M =
Ι
/
Ι
s
Curve description Standard S
Moderately inverse IEEE 4.85
Very inverse IEEE 21.6
Extremely inverse IEEE
29.1
Inverse US
5.95
Short time inverse US
2.261
The RI curve (electromechanical) has been
included in the first stage characteristic setting
options for Phase Overcurrent and Earth Fault
protections. The curve is represented by the
following equation:
t = K x
⎝
⎜
⎜
⎛
⎠
⎟
⎟
⎞
1
0.339 -
( )
0.236/
M
in seconds
With K adjustable from 0.1 to 10 in steps of
0.05
M =
Ι
/
Ι
s