Overview

Our commitment to the HVACR industry is demonstrated by our innovative solutions and comprehensive range of packages to suit every application from communication protocols to harmonic reduction technology.  At Emerson our goal is to fully leverage the strengths and expertise of our division partners, to provide global solutions that improve human comfort, safeguard food and protect our environment.

Our Emerson Saftronics brand has been a leading provider of the broadest range of quality solid state motor controls for HVAC Industry for over three decades.

HVAC Variable Speed AC Drive Applications

Of all the applications for Variable Speed Control, Centrifugal Fans and Pumps offer the greatest potential for Energy Savings due to the nature of the load. These loads are defined as Variable Torque. Variable Toque means that the load torque requirement varies (increases) with speed.

Variable Torque Loads:

• Load requires much lower torque at low speeds than at high speeds
• Copy a complete set of parameters to other drives
• and Pump loads obey the AFFINITY LAW
• Horsepower varies approximately as the cube of the speed, and the torque varies as the square of the speed
• If the speed is reduced significantly and often the opportunity for energy savings is great

Refrigeration Variable Speed Compressors

Variable speed control compressors have potential for energy savings based upon the load. Compressors are constant torque devices and the horsepower varies directly with the speed. Half speed equals half horsepower.

• Horsepower varies directly with speed

AC

Typical AC Application

This is an example of a small air conditioning system.

Cooling Tower

Cooling Tower

The speed of the cooling tower fan is based upon the return water temperature and the set point temperature in this case 85 degrees.

Example: If the actual return water temperature is colder than the set point temperature the drive will slow the fan speed. If the temperature is hotter than the set point the drive will increase the fan speed.

The set point can either be set by the building automation system or internally using the drives own PID loop.

Chilled Water Pump

Chilled Water Pump

Exhaust Fan

Exhaust Fan

In a parking garage the exhaust fan is controlled by the drive to maintain safe levels of CO (Carbon Monoxide) in the space.

Example: CO levels increase and decrease based upon levels of activity in the garage. The CO sensor sends a signal to the drive as the levels increase or decrease. The actual level of CO is compared to the allowable level of CO (the set point) and the drive responds by increasing or decreasing the speed of the fan.

Air Handler

Air Handler