Siemens 6MD85 Manual page 456

Siprotec 5 high-voltage bay controller

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Table of Contents

Control Functions

6.9 Voltage Controller

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Figure 6-122

On-Load Tap Changer

On-load tap changers are used to set the desired tap of a stepped winding of the transformer while under

load. During switchover, the desired tap of the stepped winding is first selected by means of the tap selector.

Next, the on-load tap changer switches over from the current-carrying tap to the selected tap. During this

switchover, one tap of the stepped winding is briefly bridged by an ohmic resistor so that the load switchover

takes place without current interruption. Physically, the tap changer is installed in the transformer tank or in a

separate tank.

The Tap changer function issues the adjusting commands to the on-load tap changer and receives the corre-

sponding feedback. The function of the tap changer inside the voltage controller corresponds to that of the

separate tap changer. The higher and lower adjusting commands are generated by the voltage controller. The

Check switching authority, Control model, SBO time-out, and Feedback monitoring time

parameters are set only in the voltage controller.

You can find more information in chapter

Voltage Controller

The Voltage controller function controls the voltage within the bandwidth and within the set voltage limits.

Using the Mode parameter, you can turn the voltage controller on or off or set it for test mode.

With the Number of target voltage parameter, you can specify up to 4 target voltages. You can only

activate one of these target voltages at a time using function key, communication, or a binary input. Use the

Set point mode active parameter to specify a valid target voltage via a communication network.

If the voltage controller is switched off, adjusting commands cannot be given to the tap changer in automatic

operation or in manual operation. The set on-site or remote switching authority is independent of this.

Voltage-Controller Constellation for Grid Coupling Transformers

SIPROTEC 5, High-Voltage Bay Controller, Manual

C53000-G5040-C015-9, Edition 11.2017