Regal-Beloit GE ECM X13 - Page 7

© 2006 GE ECM by Regal-Beloit - 5 - Indoor Blower Motors v0.2
Once the motor is set-up, its programming takes over to maintain constant airflow.
Ok, how does it do this you ask, and why can’t a PSC motor do the same thing?
Let’s look at the following chart and see how the two motors perform when static
pressure changes in a system.
- Notice that the PSC motor actually moves less air (CFM) as the external
static pressure (from now on we will just call it pressure) increases. By design
that’s all it can do.
- The ECM motor is designed to maintain constant airflow throughout a wide
range of pressures (typically from .1 to .9 in. wc.).
PSC motor charts are typically listed in the OEM installation guide. They provide the
same information as the above chart, but look more like this one.
External
Static
Pressure
High
Medium
Low
0.2
1625 1520 1375
0.4
1475 1410 1225
0.6
1290 1200 1100
0.8
1120 1110 1040
1
990
950
925
Air Volume
CFM per blower speed
Air Volume vs Ext SP
900
1000
1100
1200
1300
1400
1500
1600
1700
0.0 0.2 0.4 0.6 0.8 1.0
Ext Static Pressure (" H2O)
Cu Ft/min
1-ph PSC Lo 1-ph PSC Med 1-ph PSC HI
ECM