MR TRAFOGUARD ISM, Operating Instructions Manual

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6 Functions and settings
Maschinenfabrik Reinhausen GmbH 2016 110 5163667/00 EN TRAFOGUARD® ISM®
Circulating reactive current minimization
When the Circulating reactive current parallel operation method is select-
ed, then parallel operation is carried out using the circulating reactive current
minimization method. The circulating reactive current is calculated from the
transformer currents and their phase angles. A voltage proportional to the
circulating reactive current is added to the independently regulating device
as a correction for the measurement voltage. You can use the circulating re-
active current sensitivity parameter to decrease or increase this voltage cor-
rection.
The circulating reactive current method is suited to transformers connected
in parallel with a similar nominal output and short-circuit voltage U
K
and to
vector groups with the same and different step voltages. This does not re-
quire any information about the tap position.
Note that the following prerequisites must be met for the "circulating reactive
current minimization" parallel operation method:
▪
You have to use current transformers with the same rated values for all
transformers in parallel operation.
▪ If you wish to operate in parallel operation with existing devices, you
have to activate the Retrofit TAPCON® 2xx [
► 113] parameter.
To select the circulating reactive current minimization parallel operation
method, proceed as follows:
1.
Go to Settings > Parameters > Parallel operation > Parallel opera-
tion method .
2. Select the Circulating reactive current option.
3. Press the Accept button to save the modified parameter.
To configure the circulating reactive current minimization parallel operation
method, you have to also set the following parameters:
▪
Circulating reactive current sensitivity
▪ Circul. reactive current blocking limit
Setting circulating reactive current sensitivity
You can use this parameter to set the influence of circulating reactive current
on how the control deviation is calculated. The higher the set value, the
greater the calculated control deviation as a result of circulating reactive cur-
rent.
To determine the ideal circulating reactive current sensitivity, note the rele-
vant section in the Commissioning chapter.
To set the circulating reactive current sensitivity, proceed as follows:
1.
Go to Settings > Parameters > Parallel operation >Circulating reac-
tive current sensitivity .
2. Enter the circulating reactive current sensitivity.
3. Press the Accept button to save the modified parameter.
6.6.2.1