ETE MV250P1S3 250 VA Multi-Voltage Control Transformer – 12 V / 24 V AC Output
The ETE MV250P1S3 is a 250 VA single-phase multi-voltage industrial control transformer featuring a tapped primary winding and two nominal 12 V AC secondary windings. Part of the ETE MV stock control transformer range, this model is designed for electrical panel builders, OEM machinery manufacturers and industrial automation applications requiring a configurable low-voltage AC control supply.
The transformer features 10/0/220/240 V primary terminals and 0/12 V + 0/12 V secondary terminals. Its secondary windings can be connected in parallel for a nominal 12 V AC output or in series for a nominal 24 V AC output. This allows the same transformer model to serve compatible control circuits with different AC voltage requirements.
The MV250P1S3 also incorporates a 10 V primary adjustment tap. The correct use of this tap, and the associated primary terminal connections, must be confirmed with ETE. The terminal markings should not be interpreted as a complete wiring diagram or used to infer unverified supply configurations.
With a 250 VA apparent power rating, Class E insulation and 8% voltage regulation, the MV250P1S3 offers a practical option for industrial control circuits requiring either 12 V AC or 24 V AC. Its overall dimensions are 120 × 88 × 120 mm, and its specified weight is 3.9 kg.
The transformer is listed in the ETE Stock Control Transformer Range, March 2026, with specified enclosure references of EPH 3 or EPN 2.
Key Advantages
- Selectable 12 V or 24 V AC output: Supports two common low-voltage AC control configurations.
- 250 VA rated capacity: Suitable for appropriately sized industrial control and auxiliary loads.
- Tapped primary winding: Features 10/0/220/240 V terminals.
- Primary adjustment facility: Includes a 10 V adjustment tap, subject to ETE connection confirmation.
- Dual secondary windings: Two separate nominal 12 V AC windings.
- Parallel secondary configuration: Provides a nominal 12 V AC output.
- Series secondary configuration: Provides a nominal 24 V AC output.
- Flexible OEM integration: Helps accommodate different control voltage requirements with one transformer model.
- Class E insulation: Provides the specified electrical insulation classification.
- 8% voltage regulation: Gives engineers a defined characteristic for load assessment.
- Industrial dimensions: Measures 120 × 88 × 120 mm.
- Specified weight: 3.9 kg.
- Enclosure references: EPH 3 or EPN 2.
- Stock range identification: Listed as MV250P1S3 in the March 2026 ETE price list.
Key Features
- ETE MV multi-voltage control transformer series.
- 250 VA rated apparent power.
- Single-phase transformer configuration.
- 10/0/220/240 V primary terminal arrangement.
- 10 V primary adjustment tap.
- 0/12 V + 0/12 V secondary terminal arrangement.
- Two nominal 12 V AC secondary windings.
- 12 V AC parallel secondary output.
- 24 V AC series secondary output.
- Class E insulation system.
- 8% specified voltage regulation.
- 120 × 88 × 120 mm overall dimensions.
- 3.9 kg specified weight.
- EPH 3 or EPN 2 enclosure references.
- Part of the ETE stock control transformer range.
Understanding the Tapped Primary and 10 V Adjustment Connection
The ETE MV250P1S3 has a tapped primary winding identified by the terminals 10/0/220/240 V. This arrangement provides flexibility for compatible AC supply configurations, but the correct terminal selection must follow the manufacturer's wiring diagram.
The 10 V primary adjustment tap is a specific feature of this model. Its exact use and the approved terminal combinations must be confirmed with ETE before installation. The 10 V marking should not be interpreted as an independently rated 10 V primary input.
Electrical designers should verify the intended supply voltage, primary connection and expected secondary voltage before energising the transformer. Incorrect primary wiring may produce an unsuitable output voltage or damage the equipment.
Selectable 12 V AC or 24 V AC Secondary Output
The MV250P1S3 incorporates two separate 0/12 V secondary windings. These windings provide a choice of nominal secondary output voltage through the appropriate series or parallel connection.
12 V AC Parallel Secondary Connection
For a nominal 12 V AC output, the two secondary windings are connected in parallel. When correctly connected with matching polarity, the output remains at 12 V AC and the winding current capabilities are combined within the transformer's overall rating.
Correct polarity is essential when connecting transformer windings in parallel. An incorrect connection can create excessive circulating current, overheating or transformer damage. The manufacturer's connection diagram should always be followed.
24 V AC Series Secondary Connection
For a nominal 24 V AC output, the two secondary windings are connected in series. When connected with the correct polarity, the nominal voltages of the two 12 V windings add together.
The secondary winding configuration should be selected according to the voltage requirements of the connected equipment. The 12 V and 24 V options are alternative output configurations, not two independent 250 VA supplies.
250 VA Output Capacity and Calculated Secondary Current
The MV250P1S3 has a total rated apparent power of 250 VA. The current corresponding to each nominal secondary configuration can be calculated using:
Current (A) = Apparent power (VA) ÷ Secondary voltage (V)
Calculated Current at 12 V AC
For a correctly connected 12 V AC parallel output:
250 VA ÷ 12 V = approximately 20.83 A
This represents the calculated total nominal full-load secondary current at 12 V AC, based on the complete transformer rating. It is not a separately confirmed manufacturer terminal rating.
Calculated Current at 24 V AC
For a correctly connected 24 V AC series output:
250 VA ÷ 24 V = approximately 10.42 A
This represents the calculated nominal full-load secondary current at 24 V AC, based on the complete transformer rating.
The connected load must remain within the applicable transformer rating and any manufacturer-specified winding or terminal limits. Inrush current, load characteristics and protective device selection should also be considered during electrical design.
What Does 8% Voltage Regulation Mean?
The ETE MV250P1S3 has a specified 8% voltage regulation. Voltage regulation describes the change in transformer secondary voltage between no-load and rated-load conditions under defined test conditions.
The actual secondary voltage may vary with primary supply conditions and connected load. Consequently, the nominal 12 V AC and 24 V AC outputs should not be interpreted as electronically stabilised voltages.
For control equipment with narrow operating voltage tolerances, engineers should consider the regulation characteristic and expected supply variation before selecting the transformer.
Typical Applications
- Industrial electrical control panels requiring 12 V AC or 24 V AC.
- OEM machinery incorporating configurable low-voltage AC control circuits.
- Factory automation and industrial process control equipment.
- Electrical panel-building projects requiring dual secondary windings.
- Compatible AC relay and contactor control circuits.
- Industrial switching and auxiliary electrical assemblies.
- Packaging, manufacturing and processing machinery.
- Machine control cabinets requiring a dedicated AC control supply.
- Compatible 12 V AC or 24 V AC indicators and control devices.
- Electrical installations requiring series or parallel secondary winding configurations.
- Maintenance and replacement applications requiring a compatible 250 VA multi-voltage transformer.
- Control panels where the 10 V primary adjustment tap is required and its connections have been confirmed with ETE.
Installation and Connection Considerations
Before installing the ETE MV250P1S3, confirm the available primary supply, required secondary voltage, total connected apparent power and correct winding connections.
Primary wiring: The 10/0/220/240 V terminal arrangement includes a 10 V adjustment tap. The correct primary terminal connections must be confirmed with ETE before energising the transformer.
Secondary wiring: The two 0/12 V secondary windings must be connected in parallel for a nominal 12 V AC output or in series for a nominal 24 V AC output. Correct winding polarity is essential in both configurations.
The installation should incorporate suitable primary and secondary circuit protection, appropriate conductor sizing, protective earthing where applicable, ventilation and secure mechanical mounting.
The specified EPH 3 or EPN 2 enclosure references should be checked against the intended installation requirements. An enclosure reference does not necessarily mean an enclosure is included with the transformer.
