22 Mentor ll User Guide
www.controltechniques.com Issue Number: 12
Current Overload I x t
The threshold at which I x t integration begins in parameter 05.06 is
typically 105%.
The parameter full-scale value is 1000, corresponding to 150%, so that :
05.06 threshold
This value, as with the Current Limit, must be adjusted to take account of
the actual motor full load amps by applying the factor already calculated
for Current Limit, namely, 0.89. The actual value required for this motor
and Drive combination is therefore :
700 x 0.89 =623
Set 05.06 =623
Access to these parameters
To gain access to these parameters and set the values select parameter
00 and enter 200.
This permits access to all required parameters.
7.3.2 Speed feedback
Armature Voltage Feedback
For armature voltage feedback, set parameter 03.13 =1.
For practical applications a small tolerance of 2% or 3% above the
nameplate voltage should be allowed. For an armature voltage of 500V,
set parameter 03.15 = 510 or 520.
Analog Speed Feedback
For analog tachogenerator (tachometer) feedback, set parameter 03.13
= 0 (default setting).
The default values of the speed loop proportional and integral gains are
usually satisfactory for analog feedback.
Depending on the application the characteristic behavior of the load
adjustment of the speed loop gains may be needed to obtain the
optimum dynamic performance and speed-holding.
Encoder (pulse tachometer) Speed Feedback
For encoder (pulse tachometer) feedback, set parameter 03.12 =1.
The scaling parameter, 03.14, must be adjusted to correspond with the
encoder PPR (pulses per revolution) and the intended maximum speed
of the motor in rpm :
For example:
Encoder (pulse tach.) 240PPR
Motor rated max. speed 1750rpm
Motor max. speed required 1710rpm
When this type of feedback is applied there are several additional
factors to consider. The instrument should be a dual-channel
quadrature type with line driver outputs (using RS485 line
drivers).The Mentor II on-board power supply for the encoder
(pulse tachometer) is selectable to 5V, 12V or 15V by means of the
red DIP switch on PCB MDA2B. (Refer to Figure 6-4) This supply
can deliver 300mA. It is not isolated from the Drive.
Transmission line terminating resistors should be installed on the
mounting pillars (stand-offs) provided at the lower left-hand corner
of the PCB, Figure 6-4. These resistors help to prevent line
reflections and to reduce noise pick-up into the differential receiver
on the Drive.
When an encoder (pulse tachometer) is employed, the P and I gains
should be adjusted to the following suggested values as a starting
point
03.09 = 15
03.10 = 5
Connection of the marker pulses is only necessary if the Drive is being
used in an application which requires position control such as digital lock
or spindle orientation. If marker pulses are used then the encoder must
have 1024 pulses per revolution.
7.3.3 Field current
First enable the Field Controller.
Set parameter 06.13 =1.
Current Range
The Mentor II M75 provides for a field current range of either 2A
maximum or 8A please refer to the table in the description of parameter
06.11. In the example chosen, the maximum field current is 1.85A. This
is >1.5A and <2A.
Set 06.11 = 204 to select the correct range.
Maximum Field Current
The full-scale value of the Max. Field Current parameter 06.08 is 1000.
The maximum field current of the chosen example is 1.85A. The setting
for parameter 06.08 is:
Field Weakening
Since field weakening is not employed in this particular example, set
06.07 = 1000 (default).
For details of settings and calculations for field weakening, please refer
to section 7.3.4 Field weakening .
Field Economy
For applications which involve the Drive being at zero speed no-load (i.e.
motor stopped but on stand-by) for periods in the duty cycle, provision is
made to economise on the field current. The user can set the value of
the reduced field current (parameter 06.09) and the period of time before
field current is reduced (parameter 06.12).
To employ field economy, the following settings are required:
Field Economy Time-out Enable - set 06.15 = 1
Field Economy Current
Suppose the chosen value of the reduced field current is 0.5A :
Set 06.09 =270
Test the effect by temporarily setting the Field Economy Time-out, 06.12,
to 2 seconds (06.12 = 2).Disable the Drive and monitor the current value
at parameter 06.03. Two seconds after the Drive is disabled, 06.03 will
be seen to reduce to the selected value of 06.09.
Internal Field Regulator
If Mentor II is supplied with the Internal Field Regulator, field
economy is under automatic control of the software and an
external field ON-OFF control switch (Figure 6-2 and Figure 6-3) is
not required. Link out (jumper across) terminals L11 and L12 with
wire which is capable of carrying the field current.
105 1000×
150
-----------------------------
= 700=
03.14
750x10
6
PPRx Max rpm⋅()
---------------------------------------------------
=
03.14
750x10
6
240x1710
---------------------------
1827
==
NOTE
MotorMaxFieldCurrent
FieldRange
------------------------------------------------------------------------
1.85
2.00
-----------
1000× 925==
MotorReducedFieldCurrent
MotorMaxFieldCurrent
----------------------------------------------------------------------------------------
0.5
1.85
-----------
1000× 270==
NOTE
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