ITR-9-50-DT — Electronic fan speed controller 5A, 110–240V, stepless, IP54

ITR-9-50-DT is an electronic fan speed controller for stepless speed control of single-phase voltage-controllable motors (110–240 VAC / 50–60 Hz) used in industrial and commercial ventilation systems. It is the 5A model in the ITR-9 series — a range of 5 models from 1.5A to 10A — fitted with an F 8.0A H 250 VAC internal fuse.

Universal supply with automatic voltage detection

The controller accepts supply voltages between 110 and 240 VAC / 50–60 Hz and automatically detects the available voltage — no manual configuration required when switching between 110V and 230V systems. This makes it suitable for both standard European installations (230V / 50Hz) and reduced-voltage or 60Hz installations without hardware changes.

Stepless control — precise speed adjustment

Unlike stepped controllers (which offer 3–5 fixed speed levels), the ITR-9-50-DT adjusts output voltage continuously via a potentiometer, between the preset minimum speed and maximum speed. The minimum speed is adjustable internally via a trimmer in the range 30–60% of supply voltage (factory preset to 45%). This allows precise adaptation to each installation: motors that require a higher minimum speed for reliable starting, or installations where noise at minimum speed must be limited.

Two start-up modes — kickstart and soft start

At fan start-up, the controller can operate in two modes selectable by jumper on the PCB:

Kickstart (default): the fan starts at maximum speed for 8–10 seconds, ensuring reliable start-up for high-inertia motors or high-resistance duct systems, after which it returns to the speed set by the potentiometer. Recommended for standard axial and centrifugal fans.

Soft start: the fan starts at minimum speed and ramps up progressively to the set speed in 8–10 seconds. Recommended for installations where sudden starts may cause vibration or mechanical stress.

Unregulated output 230V / 2A

In addition to the regulated motor output (terminals U1 and U2), the controller provides an additional unregulated output (terminal L1) at supply voltage (230V), with a maximum current of 2A. This allows simultaneous supply of an air valve, signal lamp, motorised damper or other auxiliary equipment — synchronised with controller operation — without requiring a separate supply for these devices.

Illuminated On/Off switch

An illuminated On/Off switch is integrated on the front panel, allowing the fan to be stopped completely without disconnecting from the mains, with a clear visual indication of operating status. On 1.5A and 3A models, the Off position can be disabled by connecting supply to terminal L1 instead of L — the fan then operates continuously at the set speed.

Construction and protection

Fire-retardant ABS plastic enclosure (UL94-V0), grey RAL 7035 — industrial standard for distribution boards and panels. IP54 protection to EN 60529 — dust and water splash protection from any direction. Operating temperature: -20°C to +35°C, relative humidity 5–95% (non-condensing). Maximum cable cross-section: 2.5 mm², cable gland clamping range 5–10 mm.

ITR-9-50-DT dimensions: 162 mm (A) × 96 mm (B) × 93 mm depth (C), mounting centres 71 mm (D) × 108.8 mm (E), screws Ø 4.2 mm.

ITR-9 series — all models:

Choosing the correct model: the controller's rated current must be equal to or greater than the motor's rated current. The ITR-9-50-DT at 5A covers the large majority of small and medium single-phase axial and centrifugal fans (up to ~1.1 kW at 230V).

FAQ 

Is it compatible with any single-phase fan? The ITR-9-50-DT is compatible with single-phase voltage-controllable motors — the most common type in residential and commercial ventilation. It is not compatible with EC (electronically commutated) motors or motors with large separate starting capacitors — these require dedicated EC controllers or frequency inverters. Check the motor type in the fan's technical data sheet before purchase.

Can I connect two fans in parallel? Yes, provided the sum of both motors' rated currents does not exceed 5A. If the sum exceeds 5A, choose the ITR-9-60-DT (6A) or ITR-9100-DT (10A) model.

What happens if I switch from kickstart to soft start? The change is made with the supply disconnected, by repositioning the jumper on the PCB. In soft start mode, at every start-up the fan will ramp up from minimum speed to the set speed in 8–10 seconds, instead of starting at maximum speed.

Can it be installed outdoors? No. The ITR-9-50-DT is for indoor use only, per manufacturer specification. IP54 provides protection against dust and occasional water splashing but not against continuous rain or external condensation.

What circuit breaker rating do I need in the distribution board? The controller has its own internal fuse (F 8.0A H 250 VAC, included). In the distribution board, protect the controller's supply circuit with a minimum 10A circuit breaker. Minimum recommended supply cable cross-section for 5A load is 1.5 mm².

How precisely can I adjust the minimum speed? The internal trimmer allows minimum speed adjustment in the range 30–60% of supply voltage. At 230V, this means an adjustable minimum output voltage between ~69V and ~138V. Factory preset is 45% (~103V). Adjustment is made with the controller powered, using an insulated screwdriver, verified with a voltmeter or by direct observation of motor speed.

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