The Inverter Out Of Balance detection (
OOBD) system uses the inverter to detect the magnitude of an out of balance while the machine controller then makes intelligent decisions on the maximum extract speed allowed.
How it works
The machine runs in drain speed for 20 seconds after which the inverter detects the size of the imbalance. Then, a millivolt (mv) output to the A/D board communicates the size of the imbalance to the machine controller.
The inverter parameter for "OOB detection speed range" (constant P2-02) must agree with the actual drain speed or the inverter OOB detection will give a false report, limiting extract speed to a lower than optimum speed.
If extract speed is being limited, check the actual drain speed frequency of the inverter and confirm that inverter parameter P2-02 is 1 Hz lower than the drain speed frequency.
For example, if the drain frequency is 17.5 Hz, set the P2-02 constant at 16.5Hz. Inverter constants supplied with the machine should already indicate the correct settings.
Speed limiting at the same value (500 rpm for example) would indicate the system is malfunctioning.
Expert Level Tool
- If the machine has a black knob door handle, go to the next step. If the door has a plunger style lock, just shut the door and go to step 4.
- Close and turn the door knob to the locked position.
- Go to outputs and turn on the door lock output.
- Press the A/D D/A button on the touch pad.
- The machine will accelerate to drain speed.
- The millivolt signal for the inverter will show on the screen in 20 seconds.
- If the mV signal is less than 200 the control will not allow extract over minimum speed. you should expect the mV signal to be about 300 to 400mV with nothing in the cylinder. Limiting extract speed begins at signals between 500 and 1000 mV, depending on model. The exact speed limiting depends on machine model. Maximum millivolt signals are about 3000 mV.
For specific model engineering documentation and technical details see the attached files.
Inverter OOBD
Most Miltouch machines use an analog signal for speed output to the inverter. This D/A connection is on connector M10, terminals 3 and 4.
If your machine uses output relay signals to select speeds at the inverter,
your machine is not equipped with OOBD.
Milnor uses proprietary software on the Yaskawa inverter. This allows programming of the P2-01 through 07 constants needed for OOBD to operate.
How OOBD Works (Sequence of Events)
The OOBD system is active during drain speed on the washer. During drain speed, the inverter is sending out an analog signal to the Miltouch A/D on M10 terminals 5 and 6. The signal output from the inverter is proportional to the out of balance detected. The signal voltage is monitored while the machine is in drain speed and is locked in during the last 5 seconds of drain. Each machine has a predetermined range of voltages for OOBD. The voltage floor for all machines is 200mV. If the locked in voltage is below 200mV, we assume the inverter is malfunctioning and limit the speed to the lowest allowable RPM. The voltage ceiling is machine model specific. As the voltage rises above 200mV the machine is allowed to run at higher rpm. Between 200 Millivolts and a preset threshold voltage for the specific machine model the machine is allowed to run a max rpm. Above the threshold voltage the machine will limit extract speed. The threshold voltages vary by model.
| Voltage Comparison | Result |
|---|
| Locked in Voltage < 200mV | Minimum Allowable RPM |
| 200mV < Locked in Voltage < Model Ceiling Voltage | Maximum Allowable RPM |
| Model Ceiling Voltage < Locked in Voltage | Speed Limited RPM |
