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ECM Motor - troubleshooting Manual
ECM MOTOR
TROUBLESHOOTING
ECM Motor Background
The ECM, or Electronically Commutated Motor, is a "smart"
motor. Meaning it can be programmed to react to specific
conditions.
The ECM is electronically adjustable with an analog signal sent
to the speed controller, or in some cases automatically adjusts
itself to conditions. The ECM motor uses a quieter soft start
when compared to standard AC motors and has much lower
power consumption. The design is a combination of a very
efficient brushless DC motor, an integrated electronic control
and extensive knowledge of the customer's application, which
is captured in the control's programming.
Price is currently using the Genteq EON motor in 1/2 HP, 3/4
HP and 1 HP sizes. Voltages for the motors are 120/240/277
VAC single phase AC.
While this motor is more complicated than a standard AC fan
motor there are many benefits. This manual will show you how
to setup, program and troubleshoot ECM motors.
There are two types of programs Price can load on to an ECM;
Constant Volume, which is Price’s default, or Constant Torque
for special situations (contact application engineering).
Constant Volume:
This programming strategy has the motor speed up or
slowdown in terms of RPM to compensate for changes in
system pressure in order to deliver a constant airflow. For
instance, on a fan powered terminal equipped with a MERV
13 filter, as the filter begins loading up with dust, the pressure
drop increases, and the ECM will speed itself up to maintain the
airflow it is set for within 5%. As the primary air valve opens and
less and less air is being pulled through the filter, and more air is
coming down the valve, the motor slows down to compensate
for less pressure drop to deliver the same airflow, within 5%.
The ECM does this by measuring its own torque and RPM in
real time and uses the application specific program created in
Price’s lab to either speed up or slow down with any changes
to either. Essentially as RPM begins to drop due to increases
in system pressure, torque increases to bring the RPM up, and
vice versa. This transition happens seamlessly as the motor is
running.
Constant Torque:
There are instances where a constant airflow program is not
desirable, and it would be preferential to have a motor that
reacts to changes in system pressure by riding the fan curve as
a ‘dumb’ AC motor would. This is the constant torque program,
where torque is held constant and RPM (and airflow) are
allowed to vary. The ECM maintains all of its other benefits such
as low power consumption compared to regular AC motors,
lower noise levels, and the ability to be electronically turned
up or down, it just won’t respond to pressure changes by
increasing or decreasing RPM to maintain airflow for any given
speed setting. While this may not be ideal for the balanced
fan terminal with filter mentioned above, it is advantageous for
any situation where airflow is being varied by another device in
series with the ECM fan, and the ECM fan is being used simply
as a booster and is expected to react to the other device by
delivering the airflow that is provided to it. An example of this
might be an application where a cleanroom requires a variable
CFM, so a single duct VAV and ECM Fan Filter Unit are used
in series. The VAV box will decide what CFM to output to the
room and the ECM fan in the Fan Filter Unit is only there to
make up the pressure drop of the filter. In this case it is not
desirable that the fan speed up as the air valve closes, the
intent is for the fan to pass the air supplied to it over the filter.
In fact if the ECM were programmed with a constant volume
program, the two pressure independent devices in series will
usually oppose one another and cause instability where both
devises constantly modulate between their upper and lower
limits.
ECM MOTOR
