gefran TPD32-EV-...-2B, Instructions Manual, Page: 299 / 504

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6.16.3.9 Procedure of calculation for initial diameter
The calculation is based on the measurement of the dancer movement from the lower fullrange position to its
central working position, and on the measurent of the angular movement of the coil during the drawing phase.
For that reason, during this period, make sure that the gear mantaining the material blocked. For this reason it
is necessary to enable the regulation of the nip-roll drive with speed reference = 0.
If line nip-rolls are controlled by dancers or load cells, it is necessary to carry out the diameter calculation of the
winders/unwinders first, then the gear.
The parameter PI central v sel must be set at 0 to avoid PI output PID being set automatically at a predefined value.
Bringing the digital input programmed as
Diameter calc
to a high logic level (+24V) , if the drive is enabled,
will start the procedures. During this phase, the parameters Enable PI PID and Enable PD PID are automati -
cally disabled.
The regulation verifies the signal coming from the dancer potentiometer. If this is higher than what is already
set in Max deviation , the motor begins following the speed reference set in Positioning speed in order to wind
the material and bring the dancer to its central position of working.
The polarity of the reference assigned to
Positioning speed will be winder / unwinder equal to the one working
as a winder.
If the initial regulation verifies that the signal coming from the potentiometer of the dancer is lower than what
already set in
Max deviation
, the motor starts running with speed reference set in
Positioning speed
in order to
unwind the material and bring the dancer on the point identified by Max deviation , at this point the reference
will be inverted to bring the dancer to its central position.
When the dancer has reached the central position, the parameter
PI output PID will be set at a value inversely
proportional to the diameter and the digital output Diameter calc st , that indicates the end of diameter calcula -
tion, will be brought to high logical level .
At this point, if Enable PI PID and/or Enable PD PID are enabled, the system passes automatically in regulation.
For this reason generally the digital inputs programmed as Diameter calc and Enable PI PID and/or Enable
PD PID
will be brought to high logic level at the same time.
The output signal Diameter calc st can be used to reset the command
Diameter calc
(this command will be
activated on the rising edge of the digital input). For that reason, it must be brought to high logical level after
the supply of the regulation part of the drive and reset once the initial calculation phase has finished.
The value of
PI output PID
will be calculated with the following formula:
PI output PID = ( Min diameter x PI top lim ) / Value of the calculated diameter
The parameters PI top limit and PI bottom limit in the menu PI controls have to be set according to the max.
and min. diameter of the roll. For better explanation, please refer to paragraph 6.16.3.10 “Application examples”.