83
14. Protective function ■
◆Speed search function
Description:The speed search function finds the actual speed of motor that is Rotational using inertia, and
then starts smoothly from that speed. When restoring power after a temporary power loss or Rotational using
inertia fan is enable. There are two ways of speed search by set Cd28.
Cd28= 0, invalid
= 1, valid, MCK feedback (above 3HP)
= 2, valid, current detection
= 3, valid, MCK disconnection start+ inertia start
■ Cd28=1
MCK feedback speed search: search motor rotoring speed by MCK feedback signal, then start operation by
the speed.
Constant
No.
Constant name Settable range Factory setting
Change during
operation
Cd28 Speed search selection 03 0 X
Cd76 Speed search operating current 0200% 120% X
Cd77 Speed search deceleration time 0.110.0 2.0S X
Cd78 Speed search waiting time 0.020.0 0.2S X
Operation
command
Output
frequency
Frequency command
Start by frequency detection
Output
voltage
Voltage recovered time
0.3sec
Cd78