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…just got better Understanding ECM Motors What does ECM mean? Electrically Commutated Motor The ECM Technology 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. 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 Rotor Construction • 3 Iron Ferrite magnets glued on rotor sleeve • Magnetized at GE Factory • Two Resilient Rings isolate the shaft from the rotor • Ball Bearings ECM Modes of Operation Control Cont… 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 Connects to Connects to Thermostat Tap Board * * OEM Specific Motor Tap Boards (or interface boards) 4 Field selectable outputs for: Purpose: Designed to convert one TSTAT input into up to 4 different field selectable outputs. • Heating • Cooling • Trim multipliers • Delay/Ramps • May also be used to enable Humidistat 24 VAC Input Selection Output full wave half wave half wave + no signal How the Tap Board Communicates with the ECM 24 VAC Input Selection* Output full wave D half wave - C B A half wave + no signal * For Cool, Heat, Adjust, Delay How is a PSC motor different than an ECM? PSC • • • • vs. ECM • • • • 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 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 Motor ECM PSC AC Power Relay Contacts AC Power Inverter Power Conditioning AC to DC Conversion Motor Interface Control HVAC System Control Start / Run Capacitor INPUTS 24Vac Compressor low /hiCalls / off Constant Fan Heat Calls low stage hi stage aux/emerg Motor Control HVAC System Control INPUTS 24 VAC Constant Fan Compressor Call Rev Valve Heat Call Capacity Select Delay selects Trim/Adjust Humidistat Available Outputs RPM OverSpeed UnderSpeed CFM Demand Variable 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? Airflow Control Tips For GE ECMTM • 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! 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 • Motor Torque is regulated at a given Phase 1 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 550 500 Input Power (watts) 450 400 P = kN^3 350 1/2 N = 1/8 P 300 1/8 X 280W = 35W 1000 RPM 280 Watts 250 200 500 RPM 35 Watts 150 100 50 0 250 300 350 400 450 500 550 600 650 700 750 RPM 800 850 900 950 1000 1050 1100 1150 ECM Advantages Efficiency gain System Pressure (Pr) 0.8 PSC ECM 0.6 0.4 408W 745W 0.2 0.0 0 1 2 3 4 5 6 7 CFM/ Watt Lower static pressure yields greater efficiency gain ECM Advantages Static-independent Airflow Set the airflow and go! 0.8 PRESSURE 0.7 System airflow is starved 0.6• insufficient cooling/heating • liquid refrigerant return 0.5 to condenser Over blowing the system • poor moisture removal • high power consumption • moisture in the duct work 0.4 Typical profile with a PSC motor 0.3 0.2 408W ® 745W ® 0.1 0 1300 1400 1500 1600 1700 1800 Airflow (CFM) 1900 2000 2100 2200 2300 2400 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%). 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 Low Voltage High Voltage 16 PIN CONNECTOR 5 PIN CONNECTOR Power Connectors Continued 5 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 16 Pin Signal Connector • Pulse Width Modulation (PWM) or • 24 VAC Thermostat Mode or • Digital Serial Interface (DSI) Operating Voltages Application Note How Does the ECM Work? The End Bell defines motor characteristics. Motor Connector Motor Section Only 3 motor sections ½, ¾, or 1 hp. The motor is really a three phase motor with a permanent magnet rotor. End Bell Assembly Troubleshooting ECM Motors There are some ECM motor testers on the market today. Troubleshooting ECM Motors 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. Troubleshooting ECM Motors Don’t judge the motor by the RPM or ramp up sequence. off All slew rates are controlled Profile A Profile B Profile C on Pre-run Short run Full capacity Time: 0 - 15 min, 16 steps Level: 6 - 100% 16 steps Off Delay Troubleshooting ECM Motors • 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. Drip Loop Electrical Connections on Bottom Troubleshooting ECM Motors 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. Troubleshooting ECM Motors Rule # 4 - ECM motors, like any motor must have a power supply. Check the incoming power supply. Inductor 5 4 3 2 1 AC Line AC Line I }V Gnd } Pin 1 & 2 must be connected together for 120Vac input applications Power Connector (viewed from plug end) Inductor is used on ¾ & 1 hp – 120 VAC applications only. Troubleshooting ECM Motors # 5 Check inductor coil TSTAT Connections Pin number 9 10 111 21 31 41 51 6 Control (male) 1 2 3 4 5 6 7 8 Connector (female) 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 + Troubleshooting ECM Motors 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. Out Adjust +/- 8 7 16 15 Out + G(fan) Y1 Cool 6 5 14 13 Y /Y2 EM Ht/W2 Delay Common 2 W /W1 4 3 2 12 11 10 24VAC (R) Common 1 1 9 Control Connector Cable Half (viewed from connector end) Heat BK/PWM (Speed) (Rev Valve) 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. Out Adjust +/- 8 7 16 15 Out + G(fan) Y1 Cool 6 5 14 13 Y /Y2 EM Ht/W2 Delay Common 2 W /W1 4 3 2 12 11 10 24VAC (R) Common 1 1 9 Control Connector Cable Half (viewed from connector end) Heat BK/PWM (Speed) (Rev Valve) Troubleshooting ECM Motors 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. Out Adjust +/- 8 7 16 15 Out + G(fan) Y1 Cool 6 5 14 13 Y /Y2 EM Ht/W2 Delay Common 2 W /W1 4 3 2 12 11 10 24VAC (R) Common 1 1 9 Control Connector Cable Half (viewed from connector end) Heat BK/PWM (Speed) (Rev Valve) Troubleshooting ECM Motors Should see 24 volts here Out Adjust +/- 8 7 16 15 Out + G(fan) Y1 Cool 6 5 14 13 Y /Y2 EM Ht/W2 Delay Common 2 W /W1 4 3 2 12 11 10 24VAC (R) Common 1 1 9 Control Connector Cable Half (viewed from connector end) Heat BK/PWM (Speed) (Rev Valve) Troubleshooting ECM Motors Energize Fan Only Switch Should see 12 volts here Out Adjust +/- 8 7 16 15 Out + G(fan) Y1 Cool 6 5 14 13 Y /Y2 EM Ht/W2 Delay Common 2 W /W1 4 3 2 12 11 10 24VAC (R) Common 1 1 9 Control Connector Cable Half (viewed from connector end) Heat BK/PWM (Speed) (Rev Valve) any questions? thank you!