This method detects the motor speed by reducing the output frequency and measuring the current. The frequency reduction
starts from the maximum output frequency or from the set frequency reference. As long as the output frequency is higher
than the rotor speed, the slip will cause a high current. The closer the output frequency comes to the rotor speed, the lower
the current draw will be. When the output current drops below the level as set in b3-02, the output frequency stops
decreasing and normal operation resumes.
The following time chart illustrates how Current Detection Speed Search operates after a momentary power loss:
AC power
supply
Output
frequency
Output
current
OFF
ON
Output frequency before
momentary power loss
Selected
frequency
reference
Min. Baseblock Time (L2-03)
Decel time
set to b3-03
Waits for twice
as long as L2-04
Speed Search operation
current set to b3-02
b3-05
Figure 5.14 Current Detection Speed Search after Power Loss
Note:
After power is restored, the drive waits until the time set to b3-05 has passed before performing Speed Search. Thereby the Speed Search
may start not at the end of L2-03 but even later.
When Speed Search is applied using an external Search command or automatically with the Run command, the drive waits
for the minimum baseblock time L2-03 before Speed Search is started. If L2-03 is smaller than the time set in parameter
b3-05, b3-05 is used as the wait time.
Run command
Output
frequency
Output current
OFF
ON
b3-02
Decel time set
set to b3-03
Waits for twice
as long as L2-04
Selected
frequency
reference
Minimum Baseblock Time
(L2-03)
Max. output frequency
or the specified
frequency reference
Figure 5.15 Current Detection Speed Search at Start or external Speed Search
Note:
When the Run command is set the drive waits until the Speed Search Wait Time (b3-05) before Speed Search is performed, even if the
Minimum Baseblock Time is set to smaller values than b3-05.
Notes on Using Current Detection Type Speed Search
• Increase the voltage recovery ramp time set to L2-04 if a Uv1 fault occurs when performing Current Detection Speed
Search.
• Shorten the Speed Search deceleration time set to b3-03 if an oL1 fault occurs while performing Current Detection Speed
Search.
• Current Detection Speed Search is not available when using Open Loop Vector Control for PM motors.
• Increase the minimum baseblock time set to L2-03 if an overcurrent fault occurs when performing Speed Search after
power is restored following a momentary power loss.
n
Activation of Speed Search
Speed Search can be activated as described below. Independent of the activation method the Speed Search type must be
selected in parameter b3-24.
1.
Automatically at every Run command (
Refer to b3-01: Speed Search Selection at Start on page 113
). With this setting
external Speed Search commands are disregarded.
2.
By digital inputs:
The following input functions for H1-
can be used.
5.2 b: Application
112
SIEP C710606 20 OYMC AC Drive - V1000 User Manual
7/16/2008-13:23
