Carrier 42C Series Product Data page 35

ECM motor control methods
There are three main control methods to control the speed
of electronically commutated motor (ECM) for desirable air-
flow for a given application.
3-discrete speed input, potentiometer field speed
adjustment — This method uses the ECM with potenti-
ometer field adjustment. The relay board will have three
main circuits for HI, MEDIUM, and LOW speed. Each of
these speeds can be adjusted by potentiometer to any value
in the motor's operating range. This will allow the custom-
ization of air flow on each speed of the fan coil unit to bet-
ter suit any requirements.
3-DISCRETE SPEED INPUT
K3
VR3
VR2
VR1
K2
K1
4-DISCRETE SPEED INPUT
24Vac Neutral
EVO/ECM
45pd-51
Status
Com
Flo0
4-discrete speed input, potentiometer field speed
adjustment, solid state (only with 24-v controls by
other option) — This is the same as 3-discrete speed in-
put but with additional fourth speed. All 4 speeds can be
adjusted by potentiometer to any value in the motor's
operating range.
Control method no. 3 — ECM variable speed (only
with 24-v controls by other option) — This method
requires 0 to 10-v signal for fan speed. It has no predeter-
mined fan speeds and will ramp the motor fan speed ac-
cording to the controller used on the fan coil unit. All ECM
motor packages use a constant torque operating mode. An
ETO request is required for pricing and availability of con-
stant airflow operation.
C3
C2
C1
CR1
FloCom Flo1 Flo2 Flo3
Flo1
Flo2 Flo3
Flo4
+5V
Flo4
35