Carrier WeatherMaker 50KCQ A04 Series Service And Maintenance Instructions page 5

ECM MOTOR
The direct-drive motor is an X13 Electronically Commutated
Motor (ECM). An ECM motor contains electronic circuitry
used to convert single-phase line AC voltage into 3-phase DC
voltage to power the motor circuit. The motor circuit is a DC
brushless design with a permanent magnet rotor. On the X13
ECM motor design, the electronic circuitry is integral to the
motor assembly and cannot be serviced or replaced separately.
208/230-v units use a 230-v motor, 460-v units use a 460-v
motor and 575-v units use a 460-v motor with an autotrans-
former. Motor power voltage is connected to motor terminals L
and N (see Fig. 6 and Fig. 7); ground is connected at terminal
G. The motor power voltage is ALWAYS present; it is not
switched off by a motor contactor.
Motor operation is initiated by the presence of a 24-v control
signal to one of the five motor communications terminals.
When the 24-v signal is removed, the motor will stop. The mo-
tor control signal is switched by the defrost board's IFO output.
Evaluating motor speed
The X13 ECM Motor uses a constant torque motor design. The
motor speed is adjusted by the motor control circuitry to main-
tain the programmed shaft torque. Consequently there is no
specific speed value assigned to each control tap setting. At the
Position 5 tap, the motor speed is approximately 1050 RPM
(17.5 r/s), but varies depending on fan wheel loading.
Selecting speed tap
The five communication terminals are each programmed to pro-
vide a different motor torque output. See Table 1. Factory default
tap selection is Position 1 for lowest torque/speed operation.
208/230, 460-v Units
575-v Units
Fig. 7 — ECM Unit Wiring
Table 1 — 50KCQ Motor Tap Programming (percent
UNIT SIZE
04
05
06
Factory Default: Tap 1 (VIO).
Selecting another speed:
1. Disconnect main power to the unit. Apply lockout/tag-out
procedures.
2. Remove the default motor signal lead (VIO) from terminal
1 at the motor communications terminal.
3. Reconnect the motor signal lead to the desired speed (ter-
minals 1 through 5).
4. Connect main power to the unit.
Motor "rocking" on start-up
When the motor first starts, the rotor (and attached wheel) will
"rock" back and forth as the motor tests for rotational direction.
Once the correct rotational direction is determined by the motor
circuitry, the motor will ramp up to the specified speed. The
"rocking" is a normal operating characteristic of ECM motors.
Troubleshooting the ECM motor
Troubleshooting the X13 ECM requires a voltmeter.
1. Disconnect main power to the unit.
2. Remove the motor power plug (including the control BRN
lead) and VIO control signal lead at the motor terminals.
3. Restore main unit power.
5
of full-load torque)
TAP 1 TAP 2 TAP 3
29 33 41
46 49 57
49 55 79
TAP 4 TAP 5
48 100
67 100
90 100