ABB REG316 4 Series - Page 278

ABB Switzerland Ltd REG 316*4 1MRB520049-Uen / Rev. F
3-240
RR'
N
N
0.7 k
Es Es
1
2
2
=´
æ
è
ç
ö
ø
÷
³W
MTR MTR'
110 V
Uis
N'
N'
110 V
Uis
12
11
=´ =´
The injection voltage Uis depends on the value of the parallel
resistor R'
Ps
and can be either 0.85 V, 1.7 V or 3.4 V.
The minimum value of the resistor R'
Ps
in relation to the corre-
sponding injection voltage Uis can be seen from the following
table. The maximum possible injection voltage should be chosen
in each case.
R'
Ps
[mW] Uis [V]
> 8 0.85
> 32 1.7
> 128 3.4
Table REX011-1
The two determination modes ‘REs-Adjust’ and ‘MTR-Adjust’
determine and display the values for REs and MTR, i.e. they
present the secondary circuit reflected on the primary system
side. Inaccuracies due to contact resistance, grounding resistor
tolerances etc., are thus automatically compensated.
Determining the values for REs and MTR by means of the de-
termination modes ‘REs-Adjust’ and ‘MTR-Adjust’ during com-
missioning is recommended in preference to calculating their
values.
As a check, calculate the values of R'
Es
and MTR' from the val-
ues given for RE and MTR in the measured value window as
follows:
R' R
N
N
Es Es
2
2
=´
æ
è
ç
ö
ø
÷
MTR'= MTR
Uis
110 V
´
In most cases, the calculated and determined values will not
agree. Discrepancies of ±20 % are acceptable. Where the dis-
crepancies — especially in the case of REs — are large, check
the actual values of the grounding resistors and the grounding
transformer.