Stall Prevention During Deceleration; Autotuning; Braking Resistor Overheating Protection; Momentary Power Loss Restart - YASKAWA Varispeed G7 Series Instruction Manual

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Stall Prevention during Deceleration

If connecting a braking resistor to discharge regenerative energy, be sure to set Stall prevention selection
during decel (L3-04) to 0 (Disabled).
IMPORTANT


Autotuning

Always perform autotuning with the motor before operating using vector control. Be sure to disconnect the
motor from the load before conducting autotuning. Conducting autotuning while the motor is connected to an
elevating machine system is dangerous because it automatically runs the motor for approximately one minute.
IMPORTANT


Braking Resistor Overheating Protection

When using a braking resistor other than the Braking Resistor Unit, provide a sequence with a thermal over-
load relay or similar means to turn off the power input to the Inverter when it detects resistor overheating. See
the Connection Diagram on page 2-8 for this sequence circuit.


Momentary Power Loss Restart

Do not use the momentary power loss restart and fault restart functions in applications for elevating machines.
Make sure that L2-01=0 and L5-01=0. If these functions are used, the motor coasts to a stop with the brake
contact open when a momentary power loss or fault occurs during operation, possibly resulting in serious acci-
dents.


Torque Limit

The torque limit values (L7-01 to L7-04) are the motor's rated torque. When there is a possibility of insuffi-
cient torque at start-up or other time, increase the Inverter capacity and set the torque limit value to between
200% and 300% (factory setting is 200%).
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If Stall prevention selection during decel (L3-04) is set to the initial value 1 (Enabled), the motor may not stop
within the specified decelerating time.
Stall prevention selection during accel (L3-01) and Stall prevention selection during running (L3-05) should be
set to their initial values 1 (Enabled) to enable these functions.
1. When the motor cannot be disconnected from the load, perform stationary autotuning (T1-01 = 1 or 4). For
G7-Series Inverters with software versions PRG 1039 and later, perform stationary autotuning 2 (T1-01 =
4). Stationary autotuning will apply current to the motor in its stopped condition and automatically measure
the motor data. In the initial running period after autotuning (T1-01 =1) (20% speed min., fixed speed for 1
s min.), the motor data measured by autotuning will automatically be corrected.
2. To improve low-speed torque characteristics using V/f control, conduct stationary autotuning for line to line
resistance only (T1-01 = 2).
3. When conducting autotuning on wound motor or other special types of motors, obtain a test report for the
motor in advance and confirm that the E2 motor constants after autotuning do not vary greatly from those
of the test report.