Section 4. Configuration of the frequency converter
4.3.6. Flying start
Flying start enables valid start-up of the motor in case initial speed of a shaft of the motor differs from zero.
Five modes of
par 1.61
are possible:
0
- function is switched off.
1
- search in one direction, search frequency from Fref or Fmax.
2
- search in two directions, search frequency from Fref or Fmax.
3
- search in one direction, search frequency from Fmax.
4
- search in two directions, search frequency from Fmax.
Search in one direction
should be used for drive systems in which in case of switching off voltage powering the motor,
loading will not result in change of a direction of the device.
Search in two directions
should be used for drive systems in which in case of switching off voltage powering the
motor, loading can result in change of a direction of the device.
In case of modes 1 and 2 search of frequency can begin from the referenced frequency Fref. or from the maximal
frequency Fmax. It depends on whether the repeated start begins:
•
After pressing a key STOP (search from Fref),
•
After restart of frequ0ency converter (search from Fmax).
For search in one direction it is recommended to set up
par 1.61
on
1
. In case of search in two directions it is necessary
to set up
par 1.61
on
2
.
4.4. Protection and blocking
4.4.1. Current, frequency and the torque
limitation
s
–
Current limit
: In order to prevent overloading of the drive or the motor you can limit maximal permissible
output current of the drive – Parameters 1.41 and 1.42 with factory options are set up to value 150 % of
nominal current of the drive. System will not allow current to increase higher then this limit.
–
Torque limit
: In order to exclude mechanical impacts of the motor and all drive system the permissible torque
on a motor shaft is set up by means of parameters 1.43 and 1.44. Standard option is 150 % from rating value
of the torque.
–
Output frequency limit
: In order to exclude possibility of setting frequency which considerably exceeds
nominal frequency of the motor, parameter 1.40 allows to limit the top limit of output frequency of the drive.
Standard option is 50 Hz. Maximal value in Vector1/vector2 operating mode is 200 Hz -
it is the absolute
maximum of output frequency in Vector mode!
4.4.2. Blocking a direction of electric motor rotation
There is a possibility of partial blocking of the drive with permission of operation only in one direction. In this
case irrespective of control signals the drive will rotate the motor only in one direction. Parameter 1.65 allows to define
this option:
"000 Reverse"
- operation in two directions (option relative)
"001 Right"
- operation in one direction
"002 Left"
- operation in one direction
The symbolic direction of rotation is shown in the lower part of the display – fig. 4.15 and fig. 3.2.
4.4.3. Blocking the drive operation
Switching on one of the arbitrary blocking described below results in electric motor stopping and makes it
impossible to start until the time of taking down blocking signal (blocking cause).
Blocking state is indicated by the going off yellow diode READY on the control panel.
External permission and blocking of operation
: Two parameters allow to define digital input which will serve as an
external signal source for permission and blocking of operation:
par. 2.111 – Blocking of operation – value „Sw.Off” (default) switches off external blocking of operation.
(possible options: Sw.Off, In.C1...In.C6),
par. 2.110 – Permission of operation - value „Sw.On” (default) permits operation in spite of state of digital
inputs (possible options:
Sw.On, In.C1...In.C6
).
Blocking from thermorelay or thermistor in the motor
: parameter 3.1 permits to switch on thermorelay
blocking(see section 4.4.4.2).
External emergency stop:
instant stop of the drive in “coast” mode (see par. 2.112 – possible options:
Sw.Off,
In.C1...In.C6
). „Sw.Off” by default – function does not operate.
Blocking from „F STOP”:
There is a built-in blockade in referencing-unit structure. It is switched on by parameter
2.14. If it is set on "No" par. 2.13 determines the minimal frequency value, below which frequency will not decrease (by
38
Frequency converter MFC710 type. TWERD Power Electronics
Fig. 4.15 – Symbol of the
converter operation status
