REG 316*4 1MRB520049-Uen / Rev. F ABB Switzerland Ltd
3-183
E. Setting instructions
Settings:
Reference current IB-Setting
Enabling current I-Start
Multiplier k1-Setting
Minimum operating time t-min
Time inverse characteristic effective tg
Maximum delay t-max
Resetting time t-Reset
The stator overload function protects stator windings against ex-
cessive temperature rise as a result of overcurrents. The func-
tion is applicable to turbo-alternators designed according to the
American standard ASA-C50.13 or a similar standard defining
overload capability.
Providing compensation using the reference value of the A/D
channel has not been made, the reference current IB for the
protection is calculated from the generator load current I
B1
,
which is usually the same as the generator rated current, and the
c.t. rated currents I
N1
and I
N2
as follows:
IB I
I
I
B
N2
N
=
1
1
The setting is the ratio IB/I
N
, where I
N
is the rated current of the
protection, otherwise “IB-Setting” would be 1.0 IN.
The multiplier k1 is 41.4 s for units designed according to ASA.
For units with a similar overload capacity:
k
mn
n
1
=
-
t
JJ
J
DD
D
[s; s; K]
where:
t : thermal time constant of the stator
DJ
m
: maximum permissible temperature rise of the stator
winding
DJ
n
: rated temperature rise of the stator winding.
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