LiftMaster 230V Transformer

LiftMaster K21-5230 Commercial Operator Transformer – 208/240V to 24VAC, 40VA

The LiftMaster K21-5230 is a replacement control transformer for compatible commercial garage-door operators requiring 208/240VAC primary power and 24VAC low-voltage control power. Its 40VA output capacity supports the specified operator control circuit when installed in an approved LiftMaster application.

This transformer is intended for exact replacement—not general-purpose voltage conversion.

Specifications

• Manufacturer: LiftMaster

• Manufacturer part number: K21-5230

• Related part number: 21-5230

• Primary input: 208/240VAC

• Secondary output: 24VAC

• Power rating: 40VA

• Frequency: 50/60 Hz

• Component type: Commercial operator control transformer

• Application: Select LiftMaster commercial door operators

• Quantity: One transformer

Compatibility

Compatibility must be verified using the operator’s model number, voltage configuration, wiring diagram and replacement-parts list.

Use this transformer only when the operator calls for K21-5230, 21-5230 or confirmed equivalent specifications. Verify:

• 208/240VAC primary supply

• 24VAC secondary requirement

• 40VA capacity

• Terminal arrangement

• Wire connections

• Mounting dimensions

• Operator model and revision

Do not substitute this component for a 115V transformer. For compatible 115V applications, see the LiftMaster K21-10340 115V Transformer.

For compatible Logic 5 systems requiring a dual-primary 120/240V, 20VA configuration, see the LiftMaster K21-14182 Transformer.

Diagnostic Note

Before replacing a burned or open transformer, inspect the control circuit, photoelectric sensors, wall controls, accessory wiring and relay connections for shorts or excessive load. Installing a new transformer without correcting the original electrical fault may cause repeated failure.

Installation and Safety

Installation involves hazardous line voltage and should be completed by a qualified commercial-door technician or licensed electrician.

Disconnect, lock out and verify the operator’s power supply before servicing. Follow the manufacturer’s wiring diagram, use the correct primary-voltage terminal and verify the secondary voltage before reconnecting the control circuit.