Yaskawa G5HHP Drive - Manual (Page 322)

Troubleshooting
9.2.7 If There is Low Speed Control Accuracy at High-speed Rotation in Open-loop Vector Control Mode
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9.2.7 If There is Low Speed Control Accuracy at High-speed Rotation in Open-loop Vec-
tor Control Mode
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The motor’s rated voltage is high.
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The Inverter’s maximum output voltage is determined by its input voltage. (For example, if 400 VAC is
input, then the maximum output voltage will be 400 VAC.) If, as a result of vector control, the output volt-
age reference value exceeds the Inverter output voltage maximum value, the speed control accuracy will
decrease. Either use a motor with a low rated voltage (i.e., a special motor for use with vector control) or
change to flux vector control.
9.2.8 If Motor Deceleration is Slow
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The deceleration time is long even when control resistance is connected.
1. “Stall prevention during deceleration enabled” is set.
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When control resistance is connected, set constant L3-04 (stall prevention selection during deceleration)
to “0” (disabled). When this constant is set to “1” (enabled, the factory-set default), control resistance is
not used.
2. The deceleration time setting is too long.
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Check the deceleration time setting (constants C1-02, C1-04, C1-06, and C1-08).
3. Motor torque is insufficient.
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If the constants are correct and there is no overvoltage fault, then the motor’s power is limited. Consider
increasing the motor capacity.
4. The torque limit has been reached.
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When a torque limit has been set in constants L7-01 to L7-04, no torque will be output beyond that limit.
This can cause the deceleration time to be too long. Check to be sure that the value set for the torque limit
is suitable.
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If the torque limit has been set by multi-function analog inputs H3-05 and H3-09 (set value: 10 to 13),
check to be sure that the analog input value is suitable.
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If the Vertical-axis Load Drops When Brake is Applied
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The sequence is incorrect.
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The Inverter goes into DC injection braking status for 0.5 seconds after deceleration is completed. (This
is the factory-set default.)
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To ensure that the brake holds, set frequency detection 2 (H2-01 = 5) for the multi-function contact output
terminals (53-57) so that the contacts will OPEN when the output frequency is greater than L4-01 (3.0 to
5.0 Hz). (The contacts will close below L4-01.)
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There is hysteresis in frequency detection 2 (L4-02 2.0 Hz) . Change the setting to approximately 0.5 Hz
if there are drops during stop. Do not use the “running” signal (H2-01 = 0) for the brake ON/OFF signal.
9.2.9 If the Motor Overheats
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The load is too big.
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If the motor load is too heavy and the motor is used with the effective torque exceeding the motor’s rated
torque, the motor will overheat. Some motor rating are given for short period performance and are not con-
tinuous ratings. Reduce the load amount by either lightening the load or lengthening the acceleration/de-
celeration time. Also consider increasing the motor capacity.
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The ambient temperature is too high.
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The motor rating is determined within a particular ambient operating temperature range. The motor will
burn out if it is run continuously at the rated torque in an environment in which the maximum ambient
operating temperature is exceeded. Lower the motor’s ambient temperature to within the acceptable ambi-
ent operating temperature range.
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The withstand voltage between the motor phases is insufficient.
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When the motor is connected to the Inverter output, a surge is generated between the Inverter switching
and the motor coil. Normally the maximum surge voltage is three times the Inverter’s input power supply
voltage (i.e., 1,400 V for 575-V class). Be sure to use a motor with a withstand voltage between the motor
phases that is greater than the maximum surge voltage. In particular, when using a 575-V class Inverter,
use a special motor for Inverters.
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