Position Indicator for Load Tap Changers
Product Announcement from Weschler Instruments
A Weschler Digital Bargraph meter can be used to indicate Load Tap Changer position on a utility power transformer. The LTC adjusts the transformer voltage in discrete steps, to compensate for line or load changes. Nominal position is at the center of the step range. To remotely display tap position, some LTCs provide a low voltage DC output from a resistive divider or potentiometer. As the tap changer moves to a different step, it selects the corresponding point on the divider. Alternately, the LTC may have a quadrature encoder or rotary transducer to sense position.
The Bargraph meter is configured to provide both a numeric step value and a bar indication of relative position. Limits can be established to warn when the LTC goes above or below specific taps (as shown in the second photo). The bar changes color to call attention to this condition and a relay closes to activate an external alarm.
Meters with a circular bar (as shown here) or straight bar (as shown below) are available, in sizes up to 10". The dial and setup are customized for the number of steps and step voltages on a specific LTC. The meter can be ordered with sensor excitation to drive the resistive divider. A digital communications option interfaces to the facility's data network. More info