92 Functionality CG Drives & Automation, 01-5980-01r2
Fig. 52 Initial voltage and start time.
Direct on-line start, DOL
If this alternative is selected the motor can be started as if it
was connected directly to the mains (when current limit
[335] disabled) or alternatively using a very fast ramp see
chapter Direct on-line start DOL with current limit, page 93
(when current limit [335] enabled).
For this type of operation:
Check whether the motor can accelerate the required load
(DOL start). This start method can also be used with
malfunctioning thyristors in case an emergency start is
required.
Fig. 53 DOL start.
Initial Torque [332]
Used with start method linear/square torque control.
End Torque at Start [333]
Used with start method linear/square torque control.
Initial Voltage [334]
Used with start method voltage control. Sets the initial
voltage level, i.e. the ramp starts ramping from this output
voltage level up to full voltage. See Fig. 52, page 92.
Current Limit [335]
A current limit can be added to all starting methods. This
regulates the current during the start ramp until full voltage
is reached. The start attempt is continued during the set start
time in menu [336]. Should the current still be at the current
limit when the start time has expired, this will be indicated
by a trip or warning message depending on the alarm action
set in menu [236]”Current Limit Alarm Action”.
Linear or square torque ramp with current
limit
The motor torque is controlled according to either a linear or
a square ramp as selected in menu [331].
The current limit regulator is activated when the current is
reaching the chosen value in [335], and switched off when
full output voltage is reached, or the start time has expired
[336].
Should the current fall to a value below the set current limit,
the current limit controller will be deactivated, and the
torque ramp reactivated. The ramp slope will increase above
Default: Lin Torq Ctr
Lin Torq Ctr 1
The motor torque is controlled according
to a linear ramp, set in menu [332] and
[333].
Sqr Torq Ctr 2
The motor torque is controlled according
to a square ramp, set in menu [332] and
[333].
Voltage Ctr 3
The motor voltage is controlled according
to a linear voltage ramp, menu [334].
DOL 4 Direct online
Voltage
Time
Start time
U
n_mot
331 Start Method
Stp Lin Torq Ctr
Default: 10%
Range: 0 - 250% of T
n
Default: 150%
Range: 0 - 250% of T
n
Default: 30%
Range: 0 - 90% of U
n_mot
[221]
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