2Understanding ECM Motors ECM is an acronym for “Electronically Communitated Motor”Later versions were called “ICM” or “ICM2” the acronym for ‘Integrated Control Motor”These acronyms are based more in marketing than in reality.By that I mean that it sounds really cool from a sale perspective, But confusing for the technician.Because--- in reality, it is simply a three phase motor with an end bell assembly that controls the frequency of the three phase power to achieve the variable speed functions.What does ECM mean?Electrically Commutated Motor
3The ECM TechnologyThe 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 motor has all the advantages of a DC Brush motor without brush wear or a commutator. Motor phases are electronically controlled using solid state switches called IGBTs.
4Control Construction Microcomputer module Power Conditioning module Encapsulated with a polyurethanecompound to protect against moisturePower Conditioning takes place on the top board. Microelectronics, covered by a polyurethane compound, are located on the bottom board. The bottom board contains the “intelligence” of the motor. It has the ability to read input commands and execute algorithms.
5Laminated, interlocked stator Steel shell, aluminum end shield, Stator ConstructionLaminated, interlocked statorSteel shell, aluminum end shield,through-bolt constructionInslot Salient woundAvailable in closed, partial, or fullyvented shellThe stator is made of thin laminations interlocked together, wound with copper wire. Inslot is a winding process where the winding needle pass around each pole piece.
6Rotor Construction Magnetized at GE Factory 3 Iron Ferrite magnets glued on rotor sleeveMagnetized at GE FactoryTwo Resilient Rings isolate the shaft from the rotorBall BearingsThe rotor is magnetized in 12 magnetic segments called “Poles” (N, S, N, S,…). Resilient rings are pieces of rubber used to prevent rotor pulsating from propagating to the load (blower).
7ECM Modes of Operation Control Cont… Thermostatic Control (TSTAT)...Most widely used in Residential systemsDiscrete field selection of airflow settings and comfort options.Direct 24 VAC interface to conventional thermostatsSupports 1 or 2 “stage” systemsSuitable for furnaces, heat pumps, and fan coils4 levels of cooling airflow + trim4 levels of heating airflow + trimEnables use of 4 unique delay profiles24 VAC – This is called thermostat mode. In this mode the motor can be connected to a 24 VAC thermostat. This slide shows a basic layout of how communication occurs with the ECM in thermostat mode or 24 VAC.Connects toConnects toThermostatTap Board *Motor* OEM Specific
8Tap Boards (or interface boards) Purpose:Designed to convert one TSTAT input into up to 4 different field selectable outputs.4 Field selectable outputs for:HeatingCoolingTrim multipliersDelay/RampsMay also be used to enable Humidistat24 VAC InputSelectionOutputfull wavehalf wave -half wave +no signal
9How the Tap Board Communicates with the ECM 24 VAC InputSelection*Outputfull waveDhalf wave -The thermostat sends one 24V AC signal to the interface board. The ECM makes use of one signal to satisfy four different possible options. The ECM can operate directly from a 24 VAC thermostat. A tap board can be used to add functionality and serve many applications with a single motor and program. This is performed by providing means to accommodate various system tonnages.Chalf wave +Bno signalA* For Cool, Heat, Adjust, Delay
10How is a PSC motor different than an ECM? vs.ECMStart-up by contact to AC lineControlled by AC lineAbrupt turn-on stress, noiseMotor speed taps are inefficient and produce only minor speed adjustmentPermanently connected to AC lineControlled by low voltage inputsMotor starts softly, ramps to speedWide and efficient airflow range between hi and low tapsMotorECMPSCAC PowerInverterPowerConditioningAC to DCConversionAC PowerRelayContactsMotorMotorControlInterfaceControlA PSC motor requires an external capacitor to start and operate, AC power is applied via relay contacts which in turn are activated by 24VAC thermostat signals. The ECM is connected to AC line all the time, start and stops and selections of airflows are controlled by 24vac signals.Start / RunCapacitorHVAC System ControlHVAC System ControlINPUTSINPUTSAvailable Outputs24 VACHeat Call24VacHeat CallsConstant FanCapacity SelectRPMCompressor Callslow stageDelay selectsOverSpeedlow /hi / offhi stageCompressor CallConstant Fanaux/emergTrim/AdjustUnderSpeedRev ValveHumidistatCFM Demand
11Variable 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.Any motor can be variable speed. Usually, we only think of DC motors as variable speed, but…Over 30 years ago, Westinghouse, used a temperature based resistor to create a load on the condenser fan motor which would lower the motor RPM in cooler weather. As the resistor got colder, the resistance would increase limiting the current draw and slow down the motor.Some of you may have seen one of these old condensers.The down side of this technology was;It lacked the accuracy and precision needed with today’s higher efficiency standards.As you limit current, you also reduce power and torque.There was also the issue of the higher motor winding temperatures.The advantages of Constant Volume with ECM technologyPrecision and accuracy over rpm and motor torque.Greatly improved efficiencyLonger motor life.Don’t laugh… I am sure some of you are questioning the longer life issue.But a little later we will get into that issue and how to make sure the motor last longer.What is the difference?
12Airflow 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!Because the ECM will deliver the commanded airflow over a wide range of static pressure too often contractors install ECMs to overcome poor ductwork practices. ECMs will run quite and with high efficiency with low external pressures.Use good duct design practices and hold static pressure to less than .8”, ideally less than .5”
13Rotor Position Sensing At any given time while the motor is running, two of the three phases are energizedThe movement of the magnetized rotor past the third phase induces a voltage,or back EMF, in this unenergized phaseThe voltage in the third phase communicates the rotor’s position to the controlMotor Torque is regulated at a givenlevel by an accurate control of thecurrent in motor phases.The microcomputer control keepstorque constant regardless ofoperating speed.Phase 1EMF (electric motive force) - the force which produces, or tends to produce, electricity, or an electric current; sometimes used to express the degree of electrification as equivalent to potential, or more properly difference of potential.Phase 3Phase 2
14How Does the ECM Sense Static Pressure? Input Power vs. RPM550500450400P = kN^31000 RPM3501/2 N = 1/8 P280 Watts3001/8 X 280W = 35WInput Power (watts)How Does the ECM Sense Static Pressure?This is a little oversimplified, but for any given application, there is a relationship between Torque, RPM, CFM, and Watts. This relationship between speed and power is a little different for each application. Which is why there are so many different ECM end bell assemblies.For example; the internal resistance in a package unit, is much different than the internal resistance in a BBC blower. This internal resistance is what creates the relationship between the RPM, CFM and Watts.Amana (and all other manufactures who use ECM motors) will set up an ECM motor in a given application (like a BBC blower for example) in a wind tunnel and plot a chart of curve similar to this one which defines the relationship between the RPM, CFM and Watts. This curve is then programmed into the ECM End bell assembly.As the ECM motor ramps up, it will increase the motor RPMs until the RPM/Watts falls within the programmed curve. The motor then levels off at that RPM/Watts setting.In addition to this we set a RPM limit on the end bell. If the motor is install in an application where the total allowable static is exceeded, the motor RPMs will continue to increase until the rev limit is hit, then the motor will back off, then rev up again. This creates a puffing sound or effect.Why is there a Rev limiter on ECM motors?The rev limiter is not set to protect the motor. In fact the motor is capable of RPMs far greater than what Amana sets.We set the rev limiter to protect the blower wheels.All blower wheels have what is called a natural frequency. At a certain RPM, which is different for each size blower wheel, the blower wheel blades responds to the vibrations caused by the RPMS and will literally come apart.With ECM motors, we can program the motors to avoid these RPM ranges.250200150500 RPM35 Watts100502503003504004505005506006507007508008509009501000105011001150RPM
15ECM Advantages Efficiency gain Lower static pressure yields greater efficiency gain
16Static-independent Airflow ECM AdvantagesStatic-independent AirflowSet the airflow and go!0.10.20.30.220.127.116.11.8130014001500160017001800190020002100220023002400408W745WSystem airflow is starvedinsufficient cooling/heatingliquid refrigerant returnto condenserOver blowing the systempoor moisture removalhigh power consumptionmoisture in the duct workPRESSURETypical profile with a PSC motorAirflow (CFM)
17Troubleshooting ECM Motors The # 1 failure of ECM motors…………… No Fault Found ! (80%)The # 2 failure of ECM Motors …………… Moisture. (16%)All other failures (4%).Remember earlier we talked about ECM motors having longer life?Starting today We can easily eliminate 96% of all ECM replacements.If we can address these two items alone, we will make the ECM motors more reliable than the standard PSC motors.
18Power Connectors Low Voltage High Voltage Connectors are keyed Don’t force in the wrong orientationPull on the plug, NOT the cableDO NOT pull power cable out duringoperation – Arching could occurWhen we begin to look at troubleshooting the motor electronically, we need to observe certain precautions. Here we show the High and Low voltage connections.Make sure the motor is off before unplugging the power cable to prevent arching.Connectors are keyed: Believe it or not field failures have been received where someone has tried to force the connectors in upside down.Low Voltage16 PIN CONNECTORHigh Voltage5 PIN CONNECTOR
19Power Connectors Continued Operating Voltages Application Note 5 Pin Power Connector120 VAC uses a jumper (red wire)Control operates at 240 VACJumper enables voltage doublerDo not apply 240 VAC with jumper installed as motor andcontrol will fail.240 VAC input does not use a JUMPER16 Pin Signal Connector120 VAC Power Connector: 120 V becomes 240 V inside the motor due to the voltage doubler240 VAC Power Connector: Used for 240 VAC input applicationsIf 240 VAC input is used with a jumper, the result will be 480 VAC in the motor and the control will be destroyed. This is VERY DANGEROUS – Never use a jumper with 240!Signal Cable: Controls motor outputPulse Width Modulation (PWM) or24 VAC Thermostat Mode orDigital Serial Interface (DSI)Operating Voltages Application Note
20How Does the ECM Work? Motor Connector 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 SectionThe End Bell defines motor characteristics;The BBC60, PHB60C, PGD60, and the GUVA115 all have the same motor section while they are each in very different applications and even different operating voltages. Only the programming of the End Bell Assembly is different.Only 3 motor sections ½, ¾, or 1 hp.Within Amana, we only use ½, ¾, or 1 hp regardless of the voltage or application. G E does offer other ECM motor for different applications, but Amana does not use them at this time.For example, in the future, you may see a smaller fractional horse power ECM motor in a condenser fan application. But not at this time.THE MOTORThe motor is really a three phase motor with a permanent magnet rotor.You may be asking your self “Why are we doing this?”First, the permanent magnet rotor allows for a near zero rotor loss, greatly increasing the efficiency.Secondly, the ECM end bell controls the power frequency to control the motor RPM. By using three phase field windings, we can program the motor for maximum RPM, Rotation, and other design behavior.If this is such a great ideal, why don’t we use permanent magnet rotors in standard three phase motors?Answer --- We need the slippage of a wound rotor in three phase motors.Zero rotor loss would create some real torque coupling issues without the ramp up features of the ECM motors.End Bell Assembly
21Troubleshooting ECM Motors There are some ECM motor testers on the market today.There are some good ECM motor Testers on the market, but do you really need one?Not if you understand the ECM motor.Don’t get me wrong. I would like to have the one on the right, It has a lot of neat functions, looks cool, and Amana will have one similar to it… someday.The one on the left will apply power to the pin for a thermostat input programmed motor. It does not provide PWM signal and is really not adequate for testing BBC motors which use the PWM technology.But you can do just as well with an understanding of the ECM motor and a simple VOM meter.The key is to understand how the ECM works.
22Troubleshooting 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.Many people ask… Why does the ECM motor rock back and forth on start up?The ECM ramp up program starts the motor off slow and with very low torque, as a result, sometimes the rotor will slip one or two cycles. We do this to make the motor more efficient.Remember the motor is basically a three phase motor and we could program the motor to launch like a dragster, but that would greatly reduce the motor efficiency, and put more stress on the blower wheel.A standard 3 phase motor draws from 270 to 400% of running load amps at start up. This is one of the behaviors of electric motors that really hurts their efficiency. By starting up the motors with this ramp up program, we are saving a lot of energy.Why does the shaft to feel rough or bumpy when turned?Remember, the motor rotor is a permanent magnet rotor. As you turn it, the magnets create a electrical current in the field windings. If this current is not allowed to bleed off, It creates a counter magnetic field, or resistance.It is true that some failures of the ECM power head can cause the motor to be very easy or very hard to turn.But, what you don’t want to do… Is to judge a motor failure by how hard it is to turn the shaft.
23Troubleshooting ECM Motors Don’t judge the motor by the RPM or ramp up sequence.offAll slew rates are controlledProfile AProfile BProfile ConDon’t judge the motor by the RPM or ramp up sequence.The programming capabilities of the ECM end bell allow for up to 16 steps or 16 different CFM levels before the motor reaches the final CFM setting. At Amana we don’t use all 16 steps but the point is, each different motor has a programmed start up sequence designed to maximize the system efficiency.Don’t replace the motor just because you think the RPM is low or high. There are too many factors which influence motor RPM.Pre-runShortrunFullcapacityOffDelayTime: min, 16 stepsLevel: % 16 steps
24Troubleshooting ECM Motors Always make sure the motor is oriented such that the connectors are on the bottomMake 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.Moisture being the number one cause of failure.We can’t stress strongly enough, the need to address this moisture issue.Always make sure the motor is oriented such that the connectors are on the bottomMake sure the electrical connections form a drip loop to prevent any moisture from running down the harness and into the end bell assembly.How many of you are saying OK I will buy into the noise and vibration issue,but how can a loose blower wheel cause a motor malfunction?This is how it works. As the motor starts to ramp up, the blower wheel shifts. This shift causes a spike or wave in the watts to the motor. The ECM see this spike and doesn’t know what to do about it and shuts down. This doesn’t happen every time you have a loose blower wheel, but it does happen sometimes.You just want to be aware that it can happen.Drip LoopElectrical Connections on Bottom
25Troubleshooting 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.So far I have told you what not to look for and you are still asking your self; How do I test an ECM motor?Rule # 1 – If the motor is running at all. The problem is not in the motor. 96% of the time.This is a big statement, how can I justify this?What is the #1 & #2 failure modes? No Fault found and Moisture.Secondly, When the control fails what is the most likely component(s) to fail? The line voltage controls. When these fail, the motor will not run.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.The only exception to this would be if someone has already changed the motor or end bell and installed an incorrect end bell assembly.For Example if someone went out and replaced a BBC motor with a PGD motor thinking there was no difference between the two motors.If someone did this, What do you think the results would be? Why.Rule # 3 – What is the most common failure mode? Water. Look for signs of moisture damage and correct before replacing end bell.Even if you have determined that the interface or control board has failed….Check the end bell for moisture.Moisture is the # 1 cause of failure and if the end bell shorts out, it can cause a failure of the control or interface board.Always check for sign of moisture inside the end bell.
26Troubleshooting ECM Motors Rule # 4 - ECM motors, like any motor must have a power supply. Check the incoming power supply.InductorIAC LineGndPin 1 & 2 must be connected together for 120Vac input applicationsAC Line54321} VRule # 4 - ECM motors like any motor must have a power supply. Check the incoming power supply to the motor. Unplug the 5 Pin connector at the motor and check for incoming power.Caution !! You will be checking this with line voltage present. Exercise appropriate caution.The line voltage to the motor is not switched. There should be power to the motor, any time there is power to the unit.The inductor shown, is used on ¾ & 1 hp – 120 volt applications only. The inductor is a current limiting device used to reduce the inrush current during start up. This also reduces the minimum circuit Ampacity for the furnace. That means you can’t remove the inductor after installation.½ HP and 208/230 volt applications do not have an inductor as shown in the example.}Power Connector(viewed from plug end)Inductor is used on ¾ & 1 hp – 120 VAC applications only.
27Troubleshooting ECM Motors # 5 Check inductor coilRule # 4 - ECM motors like any motor must have a power supply. Check the incoming power supply to the motor. Unplug the 5 Pin connector at the motor and check for incoming power.Caution !! You will be checking this with line voltage present. Exercise appropriate caution.The line voltage to the motor is not switched. There should be power to the motor, any time there is power to the unit.The inductor shown, is used on ¾ & 1 hp – 120 volt applications only. The inductor is a current limiting device used to reduce the inrush current during start up. This also reduces the minimum circuit Ampacity for the furnace. That means you can’t remove the inductor after installation.½ HP and 208/230 volt applications do not have an inductor as shown in the example.
28TSTAT ConnectionsPin numberCommon C W/W Common C Delay tap select Cool tap Select Y Adjust tap select Output Return valve (heat pump only) Humidistat (BK) Heat tap select VAC (R) nd stage heat (EM/W2) nd stage cool (Y/Y2) Fan (G) Output +Control (male)Connector (female)
29Troubleshooting 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.Out8543216716Out +Adjust +/-15G(fan)Y114Y /Y2Cool13EM Ht/W2Delay1224VAC (R)Common 211HeatW /W110BK/PWM (Speed)Common 19(Rev Valve)ECM motors do not function well with cheep thermostats or power robbing thermostats.These thermostats can drive you crazy trying to troubleshoot problems because they can bleed enough voltage to cause intermittent problems or false signals.One of the first steps in troubleshooting is to disconnect the thermostat from the unit. Use a handy box or jumper wires to provide thermostat input.This is especially true if you are using a non-Amana thermostat. What you want to do is to take the thermostat out of the equation. Make certain the problem is in the unit, not false signals from the thermostat.Control Connector Cable Half(viewed from connector end)
30Troubleshooting 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.Out8543216716Out +Adjust +/-15G(fan)Y114Y /Y2Cool13EM Ht/W2Delay1224VAC (R)Common 211HeatW /W110BK/PWM (Speed)Common 19(Rev Valve)Check power to control. Pins 1 to 12 and 3 to 12. You must have 24 VAC.The motor control (end bell) must have power to function, Pins 1 to 12 and 3 to 12 must have 24 volts anytime there is power to the unit.Set thermostat to demand for cooling. Check for 24 VAC at pins 1 to 6 and 3 to 6.You are looking for a clean signal for the motor to operate to cooling speed. You could also check for heat signal (pins 1 to 2 or 3 to 2) or fan only signal (pins 1 to 15 and 3 to 15). The point is, if the motor operates in any one mode, it will operate in all the other modes.Remember back earlier in this discussion. Moisture is the # 1 failure, and in almost all failures the line voltage components failed. Either it runs or it doesn’t.If you don’t record voltage as noted, repeat test at control or interface board.Why would I want you to do this? (you are Checking the harness)If you record voltage the the control board, what does it tell you? (Harness is bad)Control Connector Cable Half(viewed from connector end)
31Troubleshooting 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.Out8543216716Out +Adjust +/-15G(fan)Y114Y /Y2Cool13EM Ht/W2Delay1224VAC (R)Common 211HeatW /W110BK/PWM (Speed)Common 19(Rev Valve)If control is defective, remove end bell and inspect for moisture before replacing control board.WHY ???You checked it out and the control is bad, so why are you playing around with the motor?(If the motor shorts out, it may cause the control or interface to fail)Do not apply power to pins 8 or 16.What does 8 & 16 do anyway?(pins 8 and 16 provide the output for the CFM light flash)Do not apply line voltage to control connections.Either of these actions will cause immediate failure of the end bell assembly.Control Connector Cable Half(viewed from connector end)
32Troubleshooting ECM Motors Out8543216716Out +Adjust +/-15G(fan)Y114Y /Y2Cool13EM Ht/W2Delay1224VAC (R)Common 211HeatW /W110BK/PWM (Speed)Should see 24 volts hereCommon 19(Rev Valve)If control is defective, remove end bell and inspect for moisture before replacing control board.WHY ???You checked it out and the control is bad, so why are you playing around with the motor?(If the motor shorts out, it may cause the control or interface to fail)Do not apply power to pins 8 or 16.What does 8 & 16 do anyway?(pins 8 and 16 provide the output for the CFM light flash)Do not apply line voltage to control connections.Either of these actions will cause immediate failure of the end bell assembly.Control Connector Cable Half(viewed from connector end)
33Troubleshooting ECM Motors Energize Fan Only SwitchOut8543216716Out +Adjust +/-15G(fan)Y114Y /Y2Cool13EM Ht/W2Delay1224VAC (R)Common 211HeatW /W110BK/PWM (Speed)Should see 12 volts hereCommon 19(Rev Valve)If control is defective, remove end bell and inspect for moisture before replacing control board.WHY ???You checked it out and the control is bad, so why are you playing around with the motor?(If the motor shorts out, it may cause the control or interface to fail)Do not apply power to pins 8 or 16.What does 8 & 16 do anyway?(pins 8 and 16 provide the output for the CFM light flash)Do not apply line voltage to control connections.Either of these actions will cause immediate failure of the end bell assembly.Control Connector Cable Half(viewed from connector end)