Hi,
Sorry if this is the wrong board. I want to create a piece of test kit to test Automatic voltage control (AVC) relays for power transformer tapchangers.
The AVC works as follows:
When the voltage is greater than desired the AVC closes a contact that energises the transformer tapchanger motor. The transformer taps down to a lower output voltage. When the voltage is lower than desired the AVC closes a contact that energises the motor in reverse therefore tapping up and increasing the voltage.
Typically the transformer has 17 different taps. The AVC knows which tap it is on by applying a voltage (typically 10v dc i think) across a series of resistor. The resistance ranges from 0 to 6400 ohms in 400 ohm steps and are brought into the circuit on a
Set of contacts that rotate as part of the tapchanger mechanism.
Essentially I need to create a variable resistance that is controlled by a 'step-up' or 'step down' input. For example the relay issues a step up command by closing a contact, the contact closes a signal to said device which increases the resistance by 400ohms. The signal will be part of the test kit ideally a dc voltage.
Any thought of how to do this would be much appreciated. I've tried google but can't see anything suitable.
I can think of a way by using relays bit it involves masses of wiring.
Thanks
Ben
Sorry if this is the wrong board. I want to create a piece of test kit to test Automatic voltage control (AVC) relays for power transformer tapchangers.
The AVC works as follows:
When the voltage is greater than desired the AVC closes a contact that energises the transformer tapchanger motor. The transformer taps down to a lower output voltage. When the voltage is lower than desired the AVC closes a contact that energises the motor in reverse therefore tapping up and increasing the voltage.
Typically the transformer has 17 different taps. The AVC knows which tap it is on by applying a voltage (typically 10v dc i think) across a series of resistor. The resistance ranges from 0 to 6400 ohms in 400 ohm steps and are brought into the circuit on a
Set of contacts that rotate as part of the tapchanger mechanism.
Essentially I need to create a variable resistance that is controlled by a 'step-up' or 'step down' input. For example the relay issues a step up command by closing a contact, the contact closes a signal to said device which increases the resistance by 400ohms. The signal will be part of the test kit ideally a dc voltage.
Any thought of how to do this would be much appreciated. I've tried google but can't see anything suitable.
I can think of a way by using relays bit it involves masses of wiring.
Thanks
Ben