Monitoring ventilation equipment in HVAC systems is essential to ensure energy efficiency, safety, and service continuity. Fans equipped with an ETRI alarm relay meet these requirements thanks to their ability to convert a tachometer signal into an on/off contact, providing instant information on the status of the fan in a heating, ventilation, and air conditioning installation.

Continuous monitoring of operation thanks to the tachometer signal

A tachometer signal generated by the fan motor provides accurate information on the actual rotation speed. To use this data in a monitoring system, the ETRI alarm relay plays an essential role: it analyzes the frequency of the tachometer pulses and determines whether the fan speed is in line with the predetermined operating speed.

When the frequency exceeds the defined threshold, the fan is considered operational. In the event of a drop in frequency (fan blocked, power loss, etc.), the relay automatically switches to fault status.

An on/off contact that can be used for simple, effective, visual signaling

The ETRI alarm relay converts tachometer information into a fully isolated on/off contact. This contact, which acts as a simple switch, is used with an external power supply to control an indicator light, buzzer, PLC, or supervision module.
This solution offers several major advantages:

• Immediate visual signaling, which is perfect for technical rooms or environments requiring rapid response.
• Enhanced safety: relay failure instantly alerts operators.

The relay's behavior can be configured according to the application: closed contact during operation and open in the event of a fault (or vice versa). This principle allows the relay to be adapted to a wide range of different HVAC installations.

An ideal solution for critical HVAC applications

Fans equipped with ETRI alarm relays are particularly suitable for installations requiring strict ventilation control, such as:

• hoods and exhaust air extraction systems,
• air handling units,
• clean rooms,
• industrial facilities or data centers,
• smoke extraction systems (depending on model and certification).

Thanks to the alarm relay, the operator can guarantee air continuity, quickly detect any rotation anomalies, and optimize preventive maintenance.

Solutions specifically designed for your needs

At ETRI, we seek the solution best suited to your ventilation needs and its integration. From the development phase onwards, please do not hesitate to contact us so that we can work together to define the best ventilation solution for your application. We will guide you in your choice of fan, which we can develop specifically for your application. Similarly, for the type of alarm outputs, we can offer you tailor-made solutions specifically adapted to the operating mode of your application.