Application Guide

63-706231
Benefits
— Reduced running costs - typical savings 40% and 14 months payback, dependent on power consumption.
— Maintenance savings arise from running the motor at reduced speed which lowers the load torque; lessens mechanical
stress on belts, bearings.
— Environmental comfort increased as a result of reduced air velocity - less draughts - and lower background noise levels.
VFD Features Used
— Soft Start - Reduced starting current and avoids pressure surges.
— Motor Speed Low Limit - Minimum air movement levels programmable.
— Automatic Continuous Operation - VFD will still run if control/speed reference signal is lost.
IMPORTANT
1. Ensure minimum airflow is maintained.
2. Beware of low air quality: See CAV + Air Quality
Operation (See Fig. 36)
Control
Output
100
Min Fan
Speed
Min OA
Damper
ZEBZEB
Setpoint
Temperature
t
OA
<
t
t
OA
>
t
Legend
Temperature Control
Fan Speed Control
Dampers
Fan Speed
Heating Cooling
OA
Damper
Fig. 36 Sequence of Control