
Transformer Accessories

Voltage control transformers are used in industrial starter circuits where the main circuit voltage is too high for use in the control circuit and where a separate control circuit feed would not be practical. Power can be tapped off of the main feed and passed through a control transformer which could then supply the lower voltage needed. Heavy electrical machinery run on higher voltages, however, the contactors that start the machinery operate at much lower voltages. Instead of running separate cables or installing extra bus bars, the main circuit voltage can be stepped down using a control transformer to the lower voltage required.
Schneider Electric’s Square D Transformer Disconnects mount inside or outside a control system enclosure and provide power to auxiliary, single-phase loads when the main three-phase disconnect is either ON or OFF. The transformer disconnect is normally wired to the line side of the control panel’s main disconnect. The 120 V power can be used for isolated or auxiliary loads, such as programmable controller equipment, portable power tools and panel lighting. The units consist of copper-wound transformers, a disconnect switch and primary and secondary fuse blocks. All blocks are installed in NEMA 1 or NEMA 12 enclosures.
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Transformers take one type of voltage and convert it to a different kind of voltage. The amount of energy being used stays the same. When voltage is increased or decreased by a transformer, the amount of energy is not increasing or decreasing, it is simply changing the way the energy is being used. Ohms law (V=IR) shows that the current will change proportionally to the voltage. Therefore when voltage increases, amperage decreases. When voltage decreases, amperage increases. A transformer can take any type of AC voltage and change that voltage either up or down. For example, power companies use transformers to change the voltage from a very high, dangerous voltage down to a level that can be safely used in homes. In industrial applications, transformers step down voltage from 480VAC to 120VAC to use in control circuits.