AC to DC Voltage Converter STU Series STU 100VA–5000VA

Description

STU series voltage converter 100VA–5000VA

• Single or twin output sockets to order
• Carrying handle up to the 3000VA frame
• Rotary input voltage selector
• ON/OFF switch with indicator
• Fuse and MCB protection
• Warranty: one year from the date of delivery

Functions

• Bidirectional conversion across the full 110–120V and 220–240V mains range.
• Primary tap selected by hand for the supply at the installation point.
• Standard positions 110V, 120V, 220V and 240V, with bespoke windings available.
• Secondary output at 110/120V or 220/240V, plus a 5A USB outlet on the case.
• Typical duty: control circuits, automation panels, sensors and small drive systems.

The STU series is a passive AC-to-AC step up and step down converter: a single-phase transformer with selectable 110 / 120 / 220 / 240V input taps, an output at 110-120V or 220-240V, and an auxiliary 5A USB outlet on the case. Because there is no switching stage, it puts no high-frequency ripple onto the supply and radiates very little, which is why it is used inside automation panels next to PLC power supplies, relays, load cells and analogue instrumentation. Models run from 100VA to 5,000VA on three enclosure frames.

Typical duty is control rails, sensor supplies, HVAC control cabinets, telecom and CCTV enclosures and small drive systems. It is not a DC power supply: where a panel also needs a regulated DC rail, specify a separate DIN-rail unit alongside it. The passive design tolerates short-circuit surges and adds no harmonic distortion, so a fault on the load does not put switching noise back onto the panel supply.

The STU series is a passive AC-to-AC step up and step down converter: a single-phase transformer with selectable 110 / 120 / 220 / 240V input taps, an output at 110-120V or 220-240V, and an auxiliary 5A USB outlet on the case. Because there is no switching stage, it puts no high-frequency ripple onto the supply and radiates very little, which is why it is used inside automation panels next to PLC power supplies, relays, load cells and analogue instrumentation. Models run from 100VA to 5,000VA on three enclosure frames.

■ How to Choose This Transformer

Panels rarely draw a steady load: a cabinet might idle at 80W and peak at 600W when several contactors pull in together. Size for the peak plus a margin, and remember that the transformer sees that peak as a step change rather than a gradual ramp. Where the peak is driven by inductive devices, include the holding current of every coil that can be energised at the same time. The 100VA to 1000VA frames cover electronics and small control circuits; 1500VA upward is for panel supply and light machinery.

Three items to settle before ordering:

• the simultaneous peak load, including coil holding currents;
• the conversion direction and the mains voltage at the panel;
• the socket standard and whether the unit will be plugged in or wired to terminals.

■ Panel Design with a Passive Transformer

Engineers choose a magnetic converter rather than a switching supply for one main reason: electrical quietness. A passive design puts no high-frequency ripple onto the supply and radiates very little, so it can share a cabinet with analogue instrumentation, load cells and signal wiring without an EMC filter. The trade-off is physical size and weight per watt. Serviceability is straightforward: fuses are accessible without removing the unit, and there are no fans or electrolytic capacitors to replace.

■ Pricing, Ordering & Quality Assurance

Step Up & Step Down Transformer Price Range (100VA–10KVA)

Pricing for the DT/ST series depends on capacity, the input/output voltage combination you need, socket type, and whether a voltage selector or MCB protection is fitted. The table below gives indicative FOB levels so you can budget before requesting a firm quotation.

* Indicative FOB Ningbo/Shanghai, standard configuration, based on 50 pcs per size. Not a formal offer — final price depends on your voltage combination, socket standard, enclosure and order quantity.

1. The efficiency of the DT/ST series is 80%. For equipment with motors or compressors, the starting current will multiply — always reserve adequate power margin.
2. Pure resistive / electronic loads: choose a transformer with capacity ≥ 1.5× the equipment rated power.
3. Inductive loads such as motors and compressors: choose a transformer with capacity ≥ 2.5–3× the equipment rated power.
4. This table is for reference only. Confirm the final solution according to the rated power and duty cycle shown on your equipment nameplate.

MOQ, Lead Time & Ordering Information

Certifications & Quality Assurance

DT/ST series step up and step down transformers are produced under our ISO 9001 quality management system, and every unit is 100% function-tested before packing.

CE Certified  |  RoHS Compliant  |  IEC Tested  |  ISO 9001  |  EMC Tested  |  12-Month Warranty

Certificates and routine test reports can be issued as PDF on request, for customs clearance, tender submissions or distributor onboarding.

■ FAQ

Is this an AC to DC converter?

The STU range is an isolating AC step up and step down transformer, catalogued on this site for control and instrumentation duty. If your load is genuinely DC, tell us the required output and we will confirm the correct product from the range.

How much margin should I leave on the rating?

At least 30 %. A passive transformer run at 70 % of its rating stays cooler, produces less noise and lasts longer than one run at its limit, particularly inside a closed cabinet.

Will it interfere with instrumentation on the same panel?

No. Being a passive magnetic device with no switching stage, it does not generate high-frequency noise and can be installed alongside analogue signal wiring.

What is the delivery time for a custom voltage?

15–25 working days for custom configurations against a minimum of fifty pieces per specification; standard models ship in 10–20 working days.

FAQ

Request Quote