B3: Speed Search - YASKAWA GA800 Programming Manual

2.3 b: Application
This function stops and restarts a coasting PM motor. The drive short circuits all the three motor phases to make
braking torque in the motor.
Set this parameter to 0.00 to disable the function.
Note:
• Short circuit Braking will let external forces rotate the PM motor. Use DC Injection Braking to prevent motor rotation from external forces.
• Motor speed and load conditions can make it necessary to install a dynamic braking option on the drive.
■
b2-13: Short Circuit Brake Time @ Stop
No.
Name
(Hex.)
b2-13 Short Circuit Brake Time @
Stop
(01BB)
This function fully stops a PM motor with a large inertia during deceleration and will not let the inertia continue to
rotate the motor.
Short Circuit Braking operates for the time set in b2-13 when output frequency is less than the value set in b2-01 [DC
Injection/Zero SpeedThreshold] or E1-09 [Minimum Output Frequency].
Set this parameter to 0.00 to disable the function.
Note:
Motor speed and load conditions can make it necessary to install a dynamic braking option on the drive.
■
b2-18: Short Circuit Braking Current
No.
Name
(Hex.)
b2-18 Short Circuit Braking
Current
(0177)
The Short Circuit Braking current cannot be higher than the drive rated current, although a higher current level can be
set using b2-18. The maximum rated current is 120% when the drive is set for Normal Duty (C6-01 = 1 [Normal Duty
Rating]). The maximum rated current is 150% when the drive is set for Heavy Duty (C6-01 = 0 [Heavy Duty
Rating]).
◆

b3: Speed Search

The Speed Search function detects the actual speed of a coasting motor, then restarts the motor before the motor stops.
Use Speed Search in these conditions:
• To continue operation after momentary power loss
• To switch from commercial power supply to drive power
• To restart a coasting fan
For example, the drive output turns off and the motor coasts when there is a momentary loss of power. After you
return power, the drive does Speed Search on the coasting motor, and restarts the motor from the detected speed.
When you use a PM motor, enable b3-01 [Speed Search at Start Selection].
There are two types of Speed Search for induction motors: Current Detection and Speed Estimation. Use parameter
b3-24 [Speed Search Method Selection] to select the type of Speed Search.
Parameter settings are different for different types of Speed Search. For details, refer to
Parameters
b3-01 [Speed Search at Start Selection]
b3-03 [Speed Search Deceleration Time]
b3-05 [Speed Search Delay Time]
210
V/f CL-V/f OLV CLV AOLV
Sets the Short Circuit Braking time at stop.
V/f CL-V/f OLV CLV AOLV
Sets the Short Circuit Braking Current as a percentage of the motor rated current.
Table 2.22 Speed Search and Related Parameters
Speed Estimation
b3-24 = 1
Description
OLV/PM AOLV/PM CLV/PM EZOLV OLV/PM
Description
OLV/PM AOLV/PM CLV/PM EZOLV OLV/PM
x
-
x
YASKAWA TOEPYAIGA8002B GA800 Drive Programming
Default
(Range)
A1-02 = 8: 0.00 s
Other than A1-02 = 8: 0.50 s
(0.00 - 25.50 s)
Default
(Range)
100.0%
(0.0 - 200.0%)
Table 2.22.
Current Detection 2
b3-24 = 2
x
x
x