Presentation on theme: "…just got better. Understanding ECM Motors What does ECM mean? Electrically Commutated Motor."— Presentation transcript:
…just got better
Understanding ECM Motors What does ECM mean? Electrically Commutated Motor
The GE ECM TM 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 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 InputSelection*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? ECM PSC vs. Power Conditioning AC to DC Conversion Interface Control Inverter Motor Control 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 Relay Contacts Motor PSC AC Power Start / Run Capacitor INPUTS 24Vac Compressor Calls low /hi / off Constant Fan Heat Calls low stage hi stage aux/emerg
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?
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 Tips For GE ECM TM 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 Phase 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 RPM Input Power (watts) 1000 RPM 280 Watts 500 RPM 35 Watts P = kN^3 1/2 N = 1/8 P 1/8 X 280W = 35W
Lower static pressure yields greater efficiency gain ECM Advantages Efficiency gain
® 408W ® 745W PRESSURE 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 Voltage 5 PIN CONNECTOR Low Voltage 16 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 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 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
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. Profile A Profile B Profile C Full capacity Off Delay Pre-run Short run Time: min, 16 steps Level: % 16 steps off on All slew rates are controlled
Troubleshooting ECM Motors Drip Loop Electrical 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.
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. AC Line Gnd Pin 1 & 2 must be connected together for 120Vac input applications } Power Connector (viewed from plug end) Inductor AC Line } V I Inductor is used on ¾ & 1 hp – 120 VAC applications only.
TSTAT Connections Pin number 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) 2 nd stage heat (EM/W2) 2 nd stage cool (Y/Y2) Fan (G) Output + Control (male) Connector (female)
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. Control Connector Cable Half (viewed from connector end) Out 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. Control Connector Cable Half (viewed from connector end) Out 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 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. Control Connector Cable Half (viewed from connector end) Out 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 Control Connector Cable Half (viewed from connector end) Out 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
Troubleshooting ECM Motors Control Connector Cable Half (viewed from connector end) Out 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