Application Guide

63-7062 36
VFD Features Used
— Power failure recovery.
— Speed search.
— Possible DC injection on start.
— Overspeed capability for increased performance.
IMPORTANT
In multi-fan applications under VFD speed control, all fans should operate in unison.
Operation (See Fig. 42)
Fan Speed Control
Condenser Water
Temperature
0
100
I
N
V
E
R
T
E
R
Full
Speed
Off
Speed
V
A
L
V
E
Open
Closed
Valve
Inverter
Minimum Sale Temperature
Condenser Temperature Reset by Wet-Bulb
Condenser Water Setpoint
}
Minimum Temperature Difference
that can be attained
Condenser Water Temperature
Outdoor Air Wet-bulb Temperature
Legend :
O.A. Wet-bulb Temperature
Fig. 42. Sequence of Control.
Primary Chilled Water Option 1 (See Fig. 43 and 44)
CC1
CC2
Evaporator 1
Evaporator 2
Fig. 43. Application without VFD.