YASKAWA A1000 Technical Manual page 304

5.9 n: Special Adjustments

n3-02: High Slip Braking Current Limit
Sets the maximum current to be output during an HSB stop as a percentage of motor rated current (E2-01). Reducing the
current limit increases the deceleration time. Make sure that this value does not exceed the drive's overload capacity.
• Lower this setting if overvoltage occurs during HSB.
• Lower this setting if motor current is too high during HSB. High current can damage the motor due to overheat.
• The default setting is 150% when the drive is set for Heavy Duty, and 120% when the drive is set for Normal Duty.
No.
n3-02

n3-03: High Slip Braking Dwell Time at Stop
When the motor reaches a relatively low speed at the end of HSB, the output frequency is kept at the minimum output
frequency E1-09 for the time set in n3-03. Increase this time if the inertia is very high and the motor is still coasting after
HSB is complete.
No.
n3-03

n3-04: High Slip Braking Overload Time
Sets the time required for an HSB overload fault (oL7) to occur when the drive output frequency does not change for
some reason during an HSB stop. This can be caused by the load rotating the motor or by excessive load inertia, resulting
in a high current. To protect the motor from overheat, the drive trips with an oL7 fault if such these conditions lasts
longer than the time set in n3-04.
No.
n3-04

Overexcitation Deceleration (Induction Motors)
Overexcitation Deceleration increases the flux during deceleration and allows shorter deceleration time settings without
the use of a braking resistor. Enabled by setting L3-04 to 4 or 5. See
Deceleration on page 283.
Notes on Overexcitation Deceleration
• As regenerative energy is mainly dissipated as heat in the motor, the motor temperature will rise if Overexcitation
Deceleration is applied frequently. In such cases, make sure the motor temperature does not exceed the maximum
allowable value or consider using a braking resistor option instead.
• During Overexcitation Deceleration 2, Hunting Prevention in V/f Control and torque limits in Open Loop Vector
Control are disabled.
• Do not use Overexcitation Deceleration in combination with a braking resistor option.
• Overexcitation Deceleration can be used in Open and Closed Loop Vector Control, but it lowers the accuracy of Torque
Control, and thereby the braking efficiency. It can be most efficiently used in a V/f Control.
• Overexcitation Deceleration cannot be used with PM motors.
Parameter Adjustments
• Use parameters n3-13 through n3-23 for adjusting Overexcitation Deceleration.
• When repetitive or long Overexcitation Deceleration results in motor overheat, lower the overexcitation gain (n3-13)
and reduce the overslip suppression current level (n3-21).
• During Overexcitation Deceleration 1 (L3-04 = 4), the drive decelerates at the active deceleration time (C1-02, C1-04,
C1-06, or C1-08). Make sure to set this time so that no overvoltage (ov) fault occurs.
• During Overexcitation Deceleration 2 (L3-04 = 5), the drive decelerates using the active deceleration time while
adjusting the deceleration rate in order to keep the DC bus voltage at the level set in L3-17. The actual stopping time
will be longer or shorter than the set deceleration time, depending on the motor characteristics and the load inertia. If
overvoltage occurs (ov), try increasing the deceleration time.
• When a Run command is entered during Overexcitation Deceleration, overexcitation operation is cancelled and the
drive will reaccelerate to the specified speed.
304
Name
High Slip Braking Current Limit
Name
High Slip Braking Dwell Time at Stop
Name
High Slip Braking Overload Time
YASKAWA ELECTRIC SIEP C710616 27G YASKAWA AC Drive A1000 Technical Manual
Setting Range
100 to 200%
Setting Range
0.0 to 10.0 s
Setting Range
30 to 1200 s
L3-04: Stall Prevention Selection during
Default
Determined by C6-01 and
L8-38
Default
1.0 s
Default
40 s