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TRIAC Dimmable PIR Sensor

TRIAC Dimmable PIR Sensor

Combining DIMAX 534 Plus with PIRAT 230V PIR Sensors

In many residential and commercial projects, there is a growing demand for simple, cost-effective lighting automation without the need for a full KNX or DALI control system. One of the most effective solutions is combining a TRIAC dimmer with a 230V PIR sensor to deliver intelligent, energy-efficient lighting control.

This article explores how to achieve this using Theben’s DIMAX 534 Plus universal dimmer and a Theben PIRAT 230V PIR sensor, creating a powerful standalone automation solution.

What is a TRIAC Dimmable PIR Setup?

A TRIAC dimmable PIR solution allows lighting to:

  • Automatically turn on when motion is detected

  • Dim or switch off after a set time delay

  • Maintain smooth dimming control for LED and traditional loads

Unlike basic on/off PIR switching, this setup enables soft start, dimming curves, and scene control, significantly improving user experience and lamp longevity.

Key Components

1. Theben DIMAX 534 Plus (TRIAC Dimmer)

The Theben DIMAX 534 Plus is a universal DIN rail dimmer designed for flexible lighting control.

Key Features:

  • Universal dimming for R, L, and C loads with automatic load detection

  • Supports trailing-edge (LED compatible) dimming up to 400W

  • Adjustable minimum brightness and dimming speed

  • Soft ON / Soft OFF for lamp protection

  • Can be controlled via push button, switch, or PIR sensor input

  • Built-in staircase lighting function with dimming fade-out

This makes it ideal for applications where you want smooth dimming rather than harsh switching.

 

2. Theben PIRAT 230V PIR Sensor

The Theben PIRAT range (e.g. PIRA series) provides reliable 230V motion detection for lighting control.

Typical Features:

  • 360° detection with coverage up to ~8m diameter (depending on model)

  • Brightness-dependent switching (lux threshold adjustable)

  • Adjustable time delay (5 seconds to 15 minutes)

  • Direct 230V relay output for switching loads

  • Suitable for LED, fluorescent, and traditional lighting loads

These sensors are ideal for corridors, bathrooms, utility rooms, and commercial spaces.

 

How the System Works

Basic Operation:

  1. The PIR detects motion and outputs a 230V switched live

  2. This signal is fed into the control input of the DIMAX 534 Plus

  3. The dimmer:

    • Turns lights ON at a preset brightness

    • Maintains output while motion is detected

    • Gradually dims down after timeout

Advantages Over Standard PIR Switching

1. Improved User Experience

Instead of lights snapping on/off:

  • Smooth fade-in on entry

  • Gentle fade-out when leaving

2. Better for LED Loads

  • Adjustable minimum levels prevent flicker

  • Trailing-edge dimming ensures compatibility

3. Energy Efficiency

  • Lights only activate when needed

  • Optional lower “standby” brightness levels

4. Flexible Control

  • Add push buttons for manual override

  • Create simple lighting “scenes” without KNX

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