ABB REG316 4 Series Operating Instructions Manual page 227

REG 316*4 1MRB520049-Uen / Rev. F
E. Setting instructions
Settings:
Reference current
Enabling current
Multiplier
Minimum operating time
Time inverse characteristic effective
Maximum delay
Resetting time
The rotor overload function protects the rotor winding of genera-
tors against excessive temperature rise as a result of overcur-
rents. The function is applicable to turbo-alternators designed
according to the American standard ASA-C50.13 or a similar
standard defining overload capability. It is connected to c.t's in
the AC excitation supply. It may nor be used for brushless exci-
tation systems.
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 AC load current I
tation supply which is usually the same as the full load excitation
current and the c.t. rated currents I
I
N2
=
IB I
B 1
I
N 1
The setting is the ratio IB/I
protection.
The multiplier k1 is 33.8 s for units designed according to ASA.
For units with a similar overload capacity:
D J - D J
m n
= t
k
1
D J
n
where:
t
: thermal time constant of the rotor
DJ
: maximum permissible temperature rise of the rotor
m
winding
DJ
: rated temperature rise of the rotor winding.
n
IB-Setting
I-Start
k1-Setting
t-min
tg
t-max
t-Reset
and I as follows:
N1 N2
, I being the rated current of the
N N
[s; s; K]
ABB Switzerland Ltd
of the exci-
B1
3-189