The term Control Transformer applies broadly to any transformer that is used to provide power to a control circuit. Control circuits often contain switches, relays, contactors, solenoids and solenoid valves, small motors and motor controls.
Within the broad grouping of Control Transformers, we have several distinct subsets:
Class 2 Transformers
These are low voltage (< 30 VRMS for dry locations), low power (< 100 VA) devices that are used in common residential, commercial, and industrial control applications including HVAC controls, Vending Machines, Appliances, Low Voltage Lighting, Alarm and
Intercom sytems. Because of their low output voltage and limited power capability, Class 2 transformer circuits
are often given special consideration in terms of circuit spacing, wiring requirements, etc.
Class 2 Transformers are covered by UL Standard 5085-3 (formerly UL 1585) and CSA C22.2 No. 66.1in North America and EN 61558-1 (formerly EN 60742) in Europe.
View UL Listed Transformer Safety Approvals
Industrial Control Transformers
This type of control transformer usually powers circuits similar to those of a Class 2 Control Transformer, but at higher power levels. Often operating at 12 V or 24 V, low voltage Industrial Control Transformers enhance safety
by isolating the control circuit from the incoming line and reducing the voltage to safer levels; however, since their output is not considered to be power limited, additional limitations apply to circuit spacing, wiring, and overload protection.
Industrial Control Transformers are covered by UL 5085-1 (formerly UL 506) and CSA C22.2 No. 66.1 in North America and EN 61558-1 (formerly EN 60742) in Europe.
Machine Tool Control Transformers
So designated because they were originally found in machine tool controls, this
category generally refers to transformers intended to reduce industrial line voltages to 120 V to operate controls and other 120 V apparatus such as motors, lighting etc. Equipment with high power requirements is often designed to be operated from 240 V or 480 V sources to reduce current requirements and increase efficiency. Often, however, 120 V is also required to power lighting, controls, and to provide convenience power for other accessories. Foster offers Machine Tool Transformers from 0.025 kVA to 5.0 kVA to fulfill these requirements.
Machine Tool Control Transformers are covered by UL 5085-1 (formerly UL 506) and CSA No. C22.2 No. 66.1 in North America and EN 61558-1 (formerly EN 60742) in Europe.
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