Staco Energy Products Co. Variable Transformer (Type 221-B)
​The device is a Staco Energy Products Co. Variable Transformer (Type 221-B). Often referred to as a “Variac,” this is a piece of electrical equipment used to vary the amount of AC voltage delivered to a device without significantly changing the frequency.
Original price was: AED 150.AED 100Current price is: AED 100.
​The device is a Staco Energy Products Co. Variable Transformer (Type 221-B). Often referred to as a “Variac,” this is a piece of electrical equipment used to vary the amount of AC voltage delivered to a device without significantly changing the frequency.
​Technical Specifications
​According to the labels on the packaging and the unit itself:
​Part Number: 221-B
​Input Voltage: 120V AC
​Phase: Single Phase (1 Phase)
​Frequency: 50/60 Hz
​Max Current: 2.5 Amps
​Capacity: 0.33 kVA (330 Volt-Amps)
​Output Voltage Options: * 0–120V: Standard range.
​0–132V: “Boost” range (available depending on how it is wired).
​Physical Construction
​The transformer is an open-frame design, meaning it is intended to be mounted inside a larger enclosure or control panel rather than used as a standalone benchtop unit.
​Core & Windings: It features a toroidal (donut-shaped) core wrapped in high-quality copper wire. A section of the insulation is ground flat to allow a carbon brush to make contact.
​Wiper Mechanism: The central shaft controls a rotating arm with a carbon brush. As you turn the shaft, the brush moves across the copper windings, “tapping” the voltage at different points.
​Terminals: There are four numbered terminals (1, 2, 3, and 4) for electrical connections. The label on the side provides a wiring guide for different output configurations.
​Mounting: It includes a threaded bushing and a shaft, designed to be mounted through a hole in a panel and secured with a nut.
​Common Applications
​Because this device allows for precise control of AC voltage, it is typically used for:
​Testing Electronics: Powering up vintage electronics slowly to avoid blowing capacitors.
​Speed Control: Adjusting the speed of certain types of AC motors (like fans).
​Heat Control: Adjusting the temperature of heating elements or hot-wire cutters.
​Lighting: Dimming high-power incandescent lighting loads.
​Safety Note: This is an autotransformer, meaning it does not provide electrical isolation from the main power line. Use with caution when testing sensitive equipment.
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