Mitsubishi Electric 700 Series Instruction Manual page 201

Causes and corrective actions
Operation panel
RB
indication
Name
Regenerative brake prealarm
Appears if the regenerative brake duty reaches or exceeds 85% of the Pr. 70 Special regenerative brake duty value.
Description
When the setting of Pr. 70 Special regenerative brake duty is the initial value (Pr. 70 = "0"), this warning does not occur. If
the regenerative brake duty reaches 100%, a regenerative overvoltage (E. OV_) occurs.
Check that the brake resistor duty is not high.
Check point
Check that the Pr. 30 Regenerative function selection and Pr. 70 Special regenerative brake duty settings are correct.
Increase the deceleration time.
Corrective action
Check that the Pr. 30 Regenerative function selection and Pr. 70 Special regenerative brake duty settings.
Operation panel
TH
indication
Name
Electronic thermal relay function prealarm
Appears if the cumulative value of the Pr. 9 Electronic thermal O/L relay reaches or exceeds 85% of the preset level. If
Description
it reaches 100% of the Pr. 9 Electronic thermal O/L relay setting, a motor overload trip (E. THM) occurs.
Check for large load or sudden acceleration.
Check point
Is the Pr. 9 Electronic thermal O/L relay setting is appropriate? (Refer to page 123)
Reduce the load and frequency of operation.
Corrective action
Set an appropriate value in Pr. 9 Electronic thermal O/L relay. (Refer to page 123)
Operation panel
MT
indication
Name
Maintenance signal output
Indicates that the cumulative energization time of the inverter has reached a given time.
Description
When the setting of Pr. 504 Maintenance timer alarm output set time is the initial value (Pr. 504 = "9999"), this warning
does not occur.
The Pr. 503 Maintenance timer setting is larger than the Pr. 504 Maintenance timer alarm output set time setting. (Refer to
Check point
page 180).
Corrective action
Setting "0" in Pr. 503 Maintenance timer erases the signal.
Operation panel
UV
indication
Name Undervoltage
If the power supply voltage of the inverter decreases, the control circuit will not perform normal functions. In addition,
the motor torque will be insufficient and/or heat generation will increase. To prevent this, if the power supply voltage
decreases below about 115VAC (about 230VAC for 400V class, about 58VAC for 100V class), this function stops the
Description
inverter output and displays
An alarm is reset when the voltage returns to normal.
Check point
Check that the power supply voltage is normal.
Corrective action
Check the power supply system equipment such as power supply.
Operation panel
SA
indication
Name
Safety stop
Description Appears when safety stop function is activated (during output shutoff). (Refer to page 24)
If the indication appears when safety stop function is not used, check that shorting wires between S1 and PC, S2 and
Check point
PC are connected.
When not using the safety stop function, short across terminals S1 and PC and across S2 and PC with shorting
wire for the inverter to run.
Corrective action
If
function (drive enabled), internal failure might be the cause. Check the wiring of terminals S1, S2 and PC and
contact your sales representative if the wiring has no fault.
196
.
is indicated when across S1 and PC and across S2 and PC are both shorted while using the safety stop