ABB REG316 4 Series Operating Instructions Manual page 277

REG 316*4 1MRB520049-Uen / Rev. F
REs and MTR in the case of secondary injection at the star-
point
An injection transformer block Type REX 011-1 is needed for this
circuit.
The bias voltage can also be injected across part of the
grounding resistor connected to the secondary of a grounding
v.t. (see Fig. 3.5.24.2).
The two resistors R'
star-point which must not exceed 20 A. The total resistance is
thus:
+
Condition 1: R' R'
Es
where: U
Gen
I
Emax
N /N
1
The following conditions must also be fulfilled:
³
Condition 2: R'
Ps
³
Condition 3: R' 4.5 R'
Es
Condition 4: R' ³
Es
The v.t. must be designed such that for a solid ground fault at
the generator terminals, the rated frequency component voltage
Us = 100 V ±20 %, i.e. the ratio MTR' = N'
the following range:
Condition 5:
N'
12
´ ³ ³
1.2 n 0.8
N'
11
N' U
12 Gen
=
A v.t.
N' 3 ´ 100 V
11
The settings for R
Es
the values of R'
Es
grounding transformer:
and R' limit the maximum current at the
Es Ps
U
Gen
³ ´
Ps
´
3 I
Emax
phase-to-phase voltage at the generator
terminals
max. star-point current = 20 A
ratio of the grounding transformer.
2
2
æ ö
N
2
W ´
130 and R'
ç ÷
è N ø
1
´
Ps
2
æ ö
N
2
0.7 k W ´ and R'
ç ÷
è N ø
1
U
´ , where n =
n
3
N
2
´
will fulfil condition 5 in most cases.
N
1
and MTR must be entered via the HMC, i.e.
and MTR' reflected to the primary of the
ABB Switzerland Ltd
2
æ ö
N
2
ç ÷
è N ø
1
æ
N
2
£ W ´
500
ç
Ps
è N
1
æ
N
£ 5.0 k W ´
ç
Es
è N
/ N' must lie within
12 11
N R'
Gen
2
´ ´
´ N R'
100 V
1 Es
2
ö
÷
ø
2
ö
2
÷
ø
1
Es
+
R'
Ps
3-239