Traffic tunnels are dangerous places, but with the addition of two critical pieces of equipment, the humble smoke spill motor can provide important safety benefits, while saving energy and money.
Underground traffic tunnels are notorious for the accumulation of smoke, dust, and other pollutants that impact the air quality and visibility within the confined environment. Any vehicle stoppages or emergencies further add pollutants to this already noxious cocktail.
A smoke spill motor’s primary role is to provide thorough ventilation and extraction within a tunnel setting to disperse any dust, toxic fumes, and pollutants from the air. Under normal operating conditions they run continuously, driven by a low voltage (LV) motor that keeps it running at a low, steady speed.
In an emergency, smoke spill motors need to be able to ramp up into ‘fire mode.’ The LV motor needs to kick into operation immediately, with a variable speed drive (VSD) supporting the jump to high speed to move contaminated air in the opposite direction of the evacuation route, dispelling the smoke, allowing safe evacuation, or even exhausting the fire entirely.
Designed to save lives
The VSD is the real hero in this application. During a fire, cables can start to burn, leading to short circuits and faults.
This would typically result in equipment tripping or shutting off altogether, however, during a fire, VSDs are designed to keep running. While they usually run on three phases, in a fire situation they can continue operating without limits. If one cable burns out, it can still run with two phases of power.
More than just air flow
Choosing the right combination of smoke spill motor, LV motor, and VSD has a big impact on your tunnel project.
The right motor will:
- Operate effectively in high temperature emergency conditions if called on to do so.
- Function effectively for the long term, limiting any unnecessary maintenance
- Run with any control system, including soft starters
By connecting a VSD with a LV motor to drive a smoke spill motor, the motor can then operate at a lower speed – which, when run day in, day out, saves significant amounts of energy. In fact, the application of a VSD could repay the cost of the equipment in less than two years.
However, this will not occur if the VSD and LV motor aren’t compatible to begin with.
Compatibility is key
The issue many companies face is this compatibility. By working with different suppliers on their projects, businesses often end up with pieces of equipment that aren’t specifically designed to work together.
If the two devices aren’t compatible, the necessary reliability cannot be guaranteed. And without reliability, what good is a fire safety system? Without reliability, you don’t get the energy savings – and it may end up costing more money in the long run.
Choosing VSDs and LV motors that are supplied by the same supplier ensures compatibility, and with compatibility comes the guarantee that the system works. It’s the rule of three – allowing you to save energy, save money, and potentially save lives.
Featured image: Toshiba’s VFAS3 variable speed drive. Image credit: Toshiba.
