Cutler-Hammer C340FG 275 VA Control Transformer

Description

Key Technical Specifications

The published C340FG specification identifies a 275 VA rating, 220–480 VAC primary, 110–120 VAC secondary, and 50/60 Hz operation.

Engineering note: The detailed public specifications available for this exact part are primarily from secondary industrial sources. Confirm the actual nameplate, terminal/tap arrangement, insulation rating, and applicable certification before installation.

Product Introduction

The Cutler-Hammer C340FG is an industrial control power transformer intended to provide an isolated lower-voltage supply for control-panel circuits. Published records specify a 275 VA capacity with a 220–480 VAC primary and 110–120 VAC secondary.

This component is relevant to legacy control cabinets where the original transformer footprint and voltage configuration must be maintained. Before replacement, verify the primary tap configuration, secondary load, mounting dimensions, terminal arrangement, and nameplate data against the installed transformer.

C340FG

C340FG

Installation & Configuration Guide

Stage 1 — Pre-Installation

1. Record the existing transformer model, nameplate voltage, VA rating, and terminal markings.
2. Photograph the complete wiring arrangement.
3. Measure the actual incoming control-panel voltage.
4. Calculate the connected secondary load in VA.
5. Confirm the replacement rating is adequate for the complete control circuit.
6. Verify the enclosure mounting arrangement and available clearance.

⚠️ Do not select the primary connection from the model number alone. Confirm the actual voltage-tap diagram on the transformer nameplate.

Stage 2 — Removal

1. Shut down the associated equipment.
2. Isolate the incoming electrical supply according to the plant’s lockout/tagout procedure.
3. Verify absence of voltage on both primary and secondary circuits.
4. Identify and label every conductor.
5. Disconnect the primary and secondary wiring.
6. Remove the mounting hardware.
7. Inspect the cabinet for heat damage, loose terminals, or insulation deterioration.

Stage 3 — Installation

1. Inspect the C340FG for physical damage and insulation deterioration.
2. Confirm the nameplate voltage and VA rating.
3. Mount the transformer securely on the panel.
4. Connect protective grounding where required by the applicable installation standard.
5. Configure the primary connection for the actual incoming voltage.
6. Connect the secondary circuit according to the original control schematic.
7. Verify conductor sizing and overcurrent protection.
8. Torque terminals according to the applicable manufacturer specification.

Stage 4 — Commissioning

1. Energize the transformer with the downstream control load isolated where practical.
2. Measure the primary voltage.
3. Measure the secondary voltage.
4. Confirm the secondary voltage is appropriate for the connected control equipment.
5. Energize the control circuit.
6. Check contactors, relays, PLC power supplies, and other loads for correct operation.
7. Monitor the transformer for abnormal heating, vibration, or noise.
8. Record the measured primary/secondary voltages and installation configuration.

Estimated replacement time: approximately 1–2 hours for a straightforward like-for-like control-transformer replacement.

⚠️ Critical: Incorrect primary-tap selection can produce excessive secondary voltage or transformer overheating. Verify the wiring diagram before applying power.

FAQ

What is the Cutler-Hammer C340FG?

The C340FG is an industrial control power transformer in the Cutler-Hammer/Eaton C340 family. Available records identify it as a 275 VA control transformer.

What is the power rating?

The published rating is 0.275 kVA, or 275 VA.

What are the primary and secondary voltages?

Available specifications list 220–480 VAC primary and 110–120 VAC secondary. The exact tap connection must be confirmed from the installed unit’s nameplate before energization.

Can the supply a PLC control cabinet?

It can provide control power where the cabinet’s voltage and load requirements match the transformer’s ratings. Calculate the total VA demand of the PLC, relays, contactors, solenoids, and other connected loads before selecting the transformer.

Is still a current-production model?

The model appears primarily in historical and secondary-market industrial records. It should be treated as a legacy component unless current Eaton documentation confirms production status.

Can I replace it with another 275 VA transformer?

Not solely on VA rating. The replacement must also match the required primary voltage/taps, secondary voltage, frequency, insulation characteristics, mounting arrangement, terminal configuration, and applicable certifications.

What condition should I specify when purchasing?

Specify New Original, New Surplus, or Refurbished/Tested. For surplus equipment, request clear photographs of the nameplate and terminal arrangement and confirm that the offered unit is specifically .

Verify precise compatibility with the transformer nameplate, control schematic, connected VA load, and applicable electrical standards before installation.