Mitsubishi Electric FR-A800 Series Beginner's Manual page 67

Protective and diagnostics functions
Error
Speed varies during
operation
Operation mode is not
changed properly
Operation panel display
is not operating
Parameter write cannot
be performed
Motor generates abnor-
mal noise
Frequency Inverters - Beginner's Guide
Possible cause Check points / Remedy
Load Check that the load is not varying.
Check that the frequency setting signal is not varying.
Check that the frequency setting signal is not affected by noise.
Input signals
Check for a malfunction due to undesirable currents when the transis-
tor output unit is connected.
Other Check that the wiring length is not too long.
Check that the STF or STR signal is OFF. When it is on, the operation
Start signal is ON
mode cannot be changed.
Check the Pr. 79 setting. When the Pr. 79 setting is "0" (initial value),
the inverter is placed in the external operation mode at input power-
Parameter setting on. Use the PU/EXT key to switch to the control unit mode.
For a description of the operation mode selection please refer to sec-
tion 6.2.7.
Connection between
The terminals PC and SD must not be connected.
terminals PC and SD
Jumper across
Check that the jumper across P1 and P/+ is connected.
P1 and P/+
Make sure that operation is not being performed (signal STF or STR is
Start signal is ON
not ON).
Press the SET key (parameter unit FR-DU08) to save the parameter set-
SET key
tings.
Check that the parameter settings are within the setting ranges.
Parameter setting
Make sure that you are not attempting to set the parameter in the
external operation mode (Pr. 79, section 6.2.7).
Parameter setting Check that the deceleration time is not too short (Pr. 8).
Troubleshooting
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