3
Ground A
Ground B
T-1
T-4
Low Speed
High Speed
L 1
L 2
Line
Motor
1
2
3
4
5
6
Together
High Speed
Line
L1
L2
L3
1
2
3
4
5
6
Open
Low Speed
Line
L1
L2
L3
Motor
Wiring
Line reactors may be required to reduce over-voltage
spikes in the motors. The motor manufacturer should be
consulted for recommended line impedence and usage of
line reactors or filters, if the lead length between the VFD
and the motor exceeds 10 feet (3m).
Fan
It is the responsibility of the installing body to perform
coast-down tests and identify any resonant frequencies
after the equipment is fully installed. These resonant fre-
quencies are to be removed from the operating range of
the fan by using the “skip frequency” function in the VFD
programming. Failure to remove resonant frequencies
from the operating range will decrease the operating life of
the fan and void the warranty.
Use of Variable Frequency Drives
Motors
Motors that are to be operated using a Variable Fre-
quency Drive (VFD) must be VFD compatible. At a mini-
mum, this must be a Premium Efficiency motor with Class F
insulation. Motors that are not supplied by Loren Cook
Company should have the recommendation of the motor
manufacturer for use with a VFD.
Grounding
The fan frame, motor and VFD must be connected to a
common earth ground to prevent transient voltages from
damaging rotating elements.
Wiring Diagrams
When ground is required, attach to ground A or B with No. 6 thread forming
screw. To reverse, interchange T-1 and T-4.
Single Speed, Single Phase Motor
When ground required, attach to ground A or B with No. 6 thread forming
screw. To reverse, interchange T-1 and T-4 leads.
2 Speed, 2 Winding, Single Phase Motor
Single Speed, Single Phase, Dual Voltage
2 Speed, 2 Winding, 3 Phase
When ground required, attach to ground A or B with No. 6 thread forming
screw. To reverse, interchange T-5 and J-10 leads.
To reverse: High Speed-interchange leads T
11
and T
12
.
Low Speed-interchange leads T
1
and T
2
. Both Speeds-interchange any 2
line leads.
2 Speed, 1 Winding, 3 Phase Motor
To reverse, interchange any 2 line leads. Motors require magnetic control.
T-1
T-4
Ground B
L 2
L1
Ground A
Line
To reverse, interchange any 2 line leads.
7
1
6
7 8 9
4 5 6
1 2
3
Low Voltage
208/230 Volts
High Voltage
460 Volts
8
2
4
9
3
5
L1
L3
L2
L1
L3
L2
3 Phase, 9 Lead Motor
Delta-Connection
4 5 6
1
7
2
8
3
9
L1 L2 L3
4 5 6
7 8 9
1 2
3
L1 L2 L3
Low Voltage
208/230 Volts
High Voltage
460 Volts
3 Phase, 9 Lead Motor
Y-Connection
Ground B
J-10
T-5
Ground A
Link A
Link B
Low Voltage
Line
L 2
L 1
Ground A
Link A & B
L1
L 2
Line
Ground B
T-5
J-10
Fan
Motor
Damper
Motor*
Second
Damper
Motor
Transformer**
Transformer**
L3
L2
L1
Typical Damper Motor Schematic
For 3 phase, damper motor voltage should be the same between L
1
and L
2
. For single phase application, dis-
regard L
3
. *Damper motors may be available in 115, 230 and 460 volt models. The damper motor nameplate
voltage should be verified prior to connection. **A transformer may be provided in some installations to correct
the damper motor voltage to the specified voltage.