Motor Connected Check
When a run command is given the drive performs it's start sequence before running. One part of the start sequence is the Motor Connected Check where a pulse of current is sent to each of the three motor phases (terminals U, V and W on the drive). This checks that all motor phases are connected before running to prevent current and voltage spikes on the motor terminals. If the drive detects that a motor phase is not connected the drive will trip to prevent running with a missing phase.
These trips can be cleared with either a stop button press, Fault Reset Function Digital Input toggle, Safety Chain toggle or a direction Digital Input toggle.
This feature is enabled by default.
Below is a guide to setup and optimise the Motor Connected Check function:
The Motor Connected Check function can be set with Parameter P10-08.
P10-08 Motor Connected Check is has a default value of 5.0% which should be sufficient to detect any missing motor phases. If your missing motor phase is not being detected you can increase P10-08 to a higher value in increments of 5%.
The ideal value should detect a missing motor phase consistently but without a loud clunk at the start.
Note
If P10-08 is set to 0.0% the Motor Connected Check is disabled and is not performed during the start sequence. This means that if a motor phase is missing the drive could potentially start and run with a missing phase.
This image shows that the drive has tripped and not released the brake if a motor phase (U in this case) is missing.
You can also see the motor never attempted to run the drive tripped and protected the motor before running with only two motor phases.
Parameter Number | Parameter Name | Units | Default | Available Settings | Access | Change During Run | Scaling | Size (Bytes) | CAN Register | CAN Sub Index | Modbus Register |
|---|---|---|---|---|---|---|---|---|---|---|---|
P10-08 | Motor Connected Check | % | 5.0% | 0.0 ... 100.0% | RW | N | 1 = 0.1 % | 2 | 23F0h | 0 | 1008 |
To ensure that the motor is connected, the drive has a function which checks that at each start command all 3 phases of the motor are connected prior to releasing the electro-mechanical brake.
This function checks for breaks in the connection between the drive and the motor, for example a broken cable or a faulty contactor.
The drive will trip “OUt-Phx” if the drive detects the motor is not connected, where x is the phase that is missing e.g. "OUt-phU"
Setting 0.0 means function is disabled.
The default value is in general suitable for most applications, this value can be reduced to reduce the audible noise when the test is performed. The correct value is one in which the audible noise level is acceptable, but the drive still detects a missing motor phase should it not be connected.
If the Motor Connected Check is active and detects that motor phases are not connected to the drive you will get these errors:
Display message | No. | Description | Corrective Action/Further information |
|---|---|---|---|
Oph-U | 85 | Output (Motor) U Phase Loss | U phase is not connected to the drive, check that output contactors are closing fully, not arcing, or not opening whilst the drive is running, and see P10-08 (Motor connected check). |
Oph-V | 86 | Output (Motor) V Phase Loss | V phase is not connected to the drive, check that output contactors are closing fully, not arcing, or not opening whilst the drive is running, and see P10-08 (Motor connected check). |
Oph-wW | 87 | Output (Motor) W Phase Loss | W phase is not connected to the drive, check that output contactors are closing fully, not arcing, or not opening whilst the drive is running, and see P10-08 (Motor connected check). |
Out-PH | 49 | Output phase loss | Check all 3 motor phases are connected, confirm that motor contactor is closing. |