…just got better. Understanding ECM Motors What does ECM mean? Electrically Commutated Motor.

…just got better

Understanding ECM Motors

What does ECM mean?

Electrically Commutated Motor

The GE ECMTM motor is a brushless DC, Three - phase motor with a permanent magnet rotor. Motor phases are sequentially energized by the electronic control, powered from a single-phase supply.

The ECM Technology

Control Construction

• Microcomputer module

• Power Conditioning module

• Encapsulated with a polyurethane

compound to protect against moisture

Stator Construction

• Laminated, interlocked stator

• Steel shell, aluminum end shield,

through-bolt construction

• Inslot Salient wound

• Available in closed, partial, or fully

vented shell

• 3 Iron Ferrite magnets glued on rotor sleeve• Magnetized at GE Factory• Two Resilient Rings isolate the shaft from the rotor• Ball Bearings

Rotor Construction

Thermostatic Control (TSTAT)...Most widely used in Residential systems

Discrete field selection of airflow settings and comfort options.• Direct 24 VAC interface to conventional thermostats• Supports 1 or 2 “stage” systems• Suitable for furnaces, heat pumps, and fan coils• 4 levels of cooling airflow + trim• 4 levels of heating airflow + trim• Enables use of 4 unique delay profiles

Thermostat Tap Board * Motor

* OEM Specific

Connects to Connects to

ECM Modes of Operation Control Cont…

Tap Boards

(or interface boards)

full wave

half wave -

half wave +

no signal

24 VAC Input

Selection Output

Purpose:

Designed to convert one TSTAT input into up to 4 different field selectable outputs.

4 Field selectable outputs for:

• Heating

• Cooling

• Trim multipliers

• Delay/Ramps

• May also be used to enable Humidistat

How the Tap Board Communicates with the ECM

full wave

half wave -

half wave +

no signal

24 VAC Input Selection* Output

* For Cool, Heat, Adjust, Delay

D

C

B

A

• Permanently connected to AC line• Controlled by low voltage inputs• Motor starts softly, ramps to speed• Wide and efficient airflow range

between hi and low taps

• Start-up by contact to AC line • Controlled by AC line • Abrupt turn-on stress, noise• Motor speed taps are inefficient and

produce only minor speed adjustment

How is a PSC motor different than an ECM?

ECMPSC vs.

PowerConditioning

AC to DCConversion

InterfaceControl

Inverter

MotorControl

AC Power

Motor

ECM

HVAC System Control

INPUTS 24 VAC Constant Fan

Rev Valve

Heat Call Capacity Select Delay selects Trim/Adjust Humidistat

Compressor Call

Available Outputs RPM OverSpeed UnderSpeed CFM Demand

HVAC System Control

RelayContacts Motor

PSCAC Power

Start / RunCapacitor

INPUTS24Vac

Compressor Calls low /hi / off

Constant Fan

Heat Calls low stage hi stage

aux/emerg

Variable Speed vs. Constant VolumeVariable Speed vs. Constant Volume

• Variable speed motor will change or vary RPM.

• Constant volume will change or vary motor RPM to deliver a preset or programmed CFM.

What is the difference?

• Low static, high quality ducted applications will run slowly, quietly and efficiently….. while delivering the correct airflow.

• High static applications will run fast, be noisy and power hungry…. The ECM may still provide the correct airflow, but at a price!

Airflow Control TipsFor GE ECMTM

Use good duct design practices and hold static pressure to less than .8”, ideally less than .5”

Rotor Position Sensing

• At any given time while the motor is running, two of the three phases are energized

• The movement of the magnetized rotor past the third phase induces a voltage,

or back EMF, in this unenergized phase

• The voltage in the third phase communicates the rotor’s position to the control

Phase 1

Phase 3

Pha

se 2

• Motor Torque is regulated at a given

level by an accurate control of the

current in motor phases.

• The microcomputer control keeps

torque constant regardless of

operating speed.

How Does the ECM Sense Static Pressure?

Input Power vs. RPM

0

50

100

150

200

250

300

350

400

450

500

550

250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150

RPM

Inp

ut

Po

we

r (w

att

s)

1000 RPM280 Watts

500 RPM35 Watts

P = kN^3

1/2 N = 1/8 P

1/8 X 280W = 35W

0.0

0.2

0.4

0.6

0.8

0 1 2 3 4 5 6 7

CFM/ Watt

Sys

tem

Pre

ssure

(Pr)

PSC

ECM

408W745W

Lower static pressure yields greater efficiency gain

ECM Advantages

Efficiency gain

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400

®408W ®745W

PR

ES

SU

RE

Airflow (CFM)

Over blowing the system • poor moisture removal • high power consumption• moisture in the duct work

System airflow is starved• insufficient cooling/heating• liquid refrigerant return to condenser

Set the airflow and go!

Typical profile with a PSC motor

ECM Advantages

Static-independent Airflow

Troubleshooting ECM Motors

The # 1 failure of ECM motors…………… No Fault Found ! (80%)

The # 2 failure of ECM Motors …………… Moisture. (16%)

All other failures (4%).

High Voltage5 PIN

CONNECTOR

Low Voltage16 PIN

CONNECTOR

Power Connectors• Connectors are keyed

• Don’t force in the wrong orientation

• Pull on the plug, NOT the cable

• DO NOT pull power cable out during

operation – Arching could occur

Power Connectors Continued5 Pin Power Connector

• 120 VAC uses a jumper (red wire)

• Control operates at 240 VAC

• Jumper enables voltage doubler

• Do not apply 240 VAC with jumper installed as motor and

control will fail.

• 240 VAC input does not use a JUMPER

• Pulse Width Modulation (PWM) or

• 24 VAC Thermostat Mode or

• Digital Serial Interface (DSI)

16 Pin Signal Connector

Operating Voltages Application Note

How Does the ECM Work?

The End Bell defines motor characteristics.

Only 3 motor sections ½, ¾, or 1 hp.

The motor is really a three phase motor with a permanent magnet rotor.

Motor Section

End Bell Assembly

Motor Connector


There are some ECM motor testers on the market today.


What is Normal?

It is normal for the blower to rock back and forth at start up.

It is normal for the shaft to feel rough or bumpy when turned.

Don’t judge the motor by the RPM or ramp up sequence.


Don’t judge the motor by the RPM or ramp up sequence.

Profile AProfile BProfile C

Fullcapacity

OffDelay

Pre-run Shortrun

Time: 0 - 15 min, 16 stepsLevel: 6 - 100% 16 steps

off

on

All slew rates are controlled


Drip LoopElectrical Connections on Bottom

• Always make sure the motor is oriented such that the connectors are on the bottom

• Make sure the electrical connections form a drip loop to prevent any moisture from running down the harness and into the end bell assembly.

• A blower wheel loose on the motor shaft can cause the blower to vibrate, excessive noise, and may cause motor malfunction.


How do we troubleshoot ECM motors?

Rule # 1 – If the motor is running at all. The problem is not in the motor.

Rule # 2 – If the motor is running at the wrong RPM/CFM, the most likely cause is the installation or controls sending signals to the ECM motor.

Rule # 3 – What is the most common failure mode? Water. Look for signs of moisture damage and correct before replacing end bell.


Rule # 4 - ECM motors, like any motor must have a power supply. Check the incoming power supply.

AC Line

Gnd

Pin 1 & 2 must be connected together for 120Vac

input applications

}

Power Connector(viewed from plug end)

54321

InductorAC Line

} V

I

Inductor is used on ¾ & 1 hp – 120 VAC applications only.

Troubleshooting ECM Motors # 5 Check inductor coil

TSTAT Connections

12345678

9 10111213141516

Pin number

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Common C1 W/W1 Common C2 Delay tap select Cool tap Select Y1 Adjust tap select Output - Return valve (heat pump only) Humidistat (BK) Heat tap select 24 VAC (R) 2nd stage heat (EM/W2) 2nd stage cool (Y/Y2) Fan (G) Output +

Control (male)

Connector (female)


Rule # 5 - ECM motors, like any motor must have a signal or switch to turn it on, or tell it to run.

Controls should be checked with a true RMS meter or analog meter.

Controls will activate at ½ nominal voltage and 12 milliamps.

Control Connector Cable Half(viewed from connector end)

8

5

4

3

2

1

6

716

13

12

11

10

9

14

15Out

Cool

Delay

Common 2

W /W1

Common 1

Y1

Adjust +/-Out +

EM Ht/W2

24VAC (R)

Heat

BK/PWM (Speed)

(Rev Valve)

Y /Y2

G(fan)

Troubleshooting ECM Motors Check power to control.

Pins 1 to 12 and 3 to 12. You must have 24 VAC.

Set thermostat to demand for cooling. Check for 24 VAC at pins 1 to 6 and 3 to 6.

If you don’t record voltage as noted, repeat test at control or interface board.


8

5

4

3

2

1

6

716

13

12

11

10

9

14

15Out

Cool

Delay

Common 2

W /W1

Common 1

Y1

Adjust +/-Out +

EM Ht/W2

24VAC (R)

Heat

BK/PWM (Speed)

(Rev Valve)

Y /Y2

G(fan)


If control is defective, remove end bell and inspect for moisture before replacing control board.

Do not apply power to pins 8 or 16.

Do not apply line voltage to control connections.


8

5

4

3

2

1

6

716

13

12

11

10

9

14

15Out

Cool

Delay

Common 2

W /W1

Common 1

Y1

Adjust +/-Out +

EM Ht/W2

24VAC (R)

Heat

BK/PWM (Speed)

(Rev Valve)

Y /Y2

G(fan)



8

5

4

3

2

1

6

716

13

12

11

10

9

14

15Out

Cool

Delay

Common 2

W /W1

Common 1

Y1

Adjust +/-Out +

EM Ht/W2

24VAC (R)

Heat

BK/PWM (Speed)

(Rev Valve)

Y /Y2

G(fan)

Should see 24 volts here



8

5

4

3

2

1

6

716

13

12

11

10

9

14

15Out

Cool

Delay

Common 2

W /W1

Common 1

Y1

Adjust +/-Out +

EM Ht/W2

24VAC (R)

Heat

BK/PWM (Speed)

(Rev Valve)

Y /Y2

G(fan)

Should see 12 volts here

Energize Fan Only Switch

thank you!

any questions?

…just got better. Understanding ECM Motors What does ECM mean? Electrically Commutated Motor.

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Transcript of …just got better. Understanding ECM Motors What does ECM mean? Electrically Commutated Motor.