GEH-6385 Reference and Troubleshooting, 2300 V Drives Chapter 3 Paramters/Functions
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3-61
Function description
The variables Phase A current, Phase B current, and Phase C current are filtered
versions of the measured phase current feedbacks. The default filter frequency is
1000 rad/sec.
When the drive is stopped, it performs an automatic current offset calculation.
During the calculati on the power bridge is turned off, and the phase currents should
be zero. Any appreciable ph ase current that is detected dur ing the calculation
indicates a potenti al power bridge or feedback circu itry problem. The Phase A cur
offset, Phase B cur offset, and Phase C cur offset trip faults are reported when
excessive offsets ar e calculated. The calculated offs ets Phs A current offset, Phs B
current offset, and Phs C current offset are used by th e control to calculate feedbacks
once the drive starts runn ing.
Timed Overcurrent Detection
The Timed Overcurrent Detection function protects the motor and wiring against
overheating caused by large currents for extended periods of time.
Function inputs
The following table specifies the input variables to the Timed Overcurrent Detection
function.
Variable Description
Phase A current Phase A current. Amps
Phase B current Phase B current. Amps
Phase C current Phase C current. Amps
Function outputs
The following table specifies the output variables to the Timed Overcurrent
Detection function.
Variable Description
Ia^2 filt ered Squared and filtered phase A current. RMS amps²
Ib^2 filt ered Squared and filtered phase B current. RMS amps²
Ic^2 filtered Squared and filtered phase C current. RMS amps²
Function configuration
The following table sp ecifies the Timed Overcurrent Detection function
configuration parameters.
Parameter Description
Disable TO C profile Disables the application of the motor cooling profile to the
squared phase currents.
Motor protect class Motor protection class.