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How a fireman’s override can help to save lives

01 September, 2022

The heatwaves over the summer were a sober reminder of the risks of fires in buildings. In the event of a fire, modern VSDs can be configured to help clear smoke, keep fire exits clear and preserve life, as Oliver Woolley, ABB’s key account manager for HVAC, explains.

Variable-speed drives (VSDs) typically feature an override mode. This mode, also known as “fireman’s override”, is a flexible way to configure a critical response. It is typically used in fan applications that require a special operating mode to assist with fire and smoke control. The override mode can also be used in a variety of other applications, in addition to fire safety control.

The override mode can allow the drive to run a motor at an adjustable, predefined or PID-controlled speed in any direction, to assist a building smoke control system during evacuation, and to help with firefighting. It increases the safety of a building’s occupants and reduces fire damage and the costs of restoration after a fire.

Drives can be programmed to ignore or reset faults to ensure a “run at all costs” operation. The override mode cannot be triggered by any other signal: once this mode is activated, the drive cannot exit it until the fire condition signal is reset by opening the contact closure or removing power from the drive.

The fireman’s override mode allows a VSD to run a motor at an adjustable, predefined or PID-controlled speed in any direction, to help a control smoke during a fire evacuation


Before using a fireman’s override system, please check local regulations and requirements.

A step-by-step guide to configuring the fireman’s override input on an ABB ACH580 drive can be seen in this video:

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