Set up AVR (automatic voltage regulator) tap changer position with mA inputs
AQ-200 series IEDs equipped with automatic voltage regulator are able to detect the tap position with mA inputs, BCD coded digital inputs and digital input voltage measurement. This guide will walk you through how to set up AVR tap changer position indication with mA inputs to an AQ-200 series IED. For more detailed description of the function please refer to IED manuals.
Enabling voltage regulator function
If the unit has voltage regulator function it can be activated at Control > Controls enabled menu. After enabling the function it will appear at Control > Control functions.
mA input options for AQ-200 series IEDs
For mA measurement AQ-200 series generally uses:
- RTD & mA input option card or
- mA output and input option cards
The used channel for tap position indication is done at Control > Control functions > Voltage regulator > INFO menu.
- If mA input on RTD & mA input card is used, choose mA internal input 7 or 8.
- If mA input on mA output and input card is used, choose "mA in 1 (card 1)" or "mA in 2(I card 2).
mA input ranges and steps
When source of mA measurement is chosen, next step is to set the measurement ranges. At Control > Control functions > Voltage regulator > INFO menu at Tap settings sections set the number of steps, tap step effect and mA input measurement range (minimum and maximum mA). Also set if tap is at maximum position when mA measurement is at minimum or maximum value.
Using mA input when tap position indication measurement isn't linear
In a lot of cases the mA signal brought to the AQ-200 unit doesn't follow a linear path between minimum and maximum mA setting. This can lead to one tap changer position change count as two or zero. This can be fixed by using a scaled curve. Go to Measurements > AI(mA, DI volt) scaling menu and enable Analog input scaling and Scaling curve 1. Then select the used mA input channel. Then add a few curve points according to mA measurement you get from different tap positions. In the example below two points have been added between the maximum and minimum point to account for the non-linear mA curve steps produce together. Then this curve is used instead of using mA measurements directly as the Tap position indication.
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