Operation; Analog Input Operation; Speed Reference; Minimum Speed - PowerTec 2000C Instruction Manual

This section addresses the use of adjustments, op-
tion jumpers, and system setup to obtain the best perfor-
mance from the Models 2000C and 3000C for your appli-
cation. After the physical and electrical installations are
done, it is desirable to "tune" the control and motor to the
process it is operating. There are some things which may
be done with the motor and control and some things which
may not be done. These things are what this section is
about.
All customer adjustments and option jumpers are on
the Speed Controller board (part #4001-141107-XXX).
There are option jumpers on some versions of the Current
Controller board (part #4001-141108-XXX), but these are
used only for testing purposes. The Current Sensor board
has calibration adjustments only. There are no customer
adjustments on the Base Driver board (part #4001-144002-
XXX). The locations of all jumpers, adjustments, and test
points are shown in the appropriate drawings in this
section and the next section.
As pointed out in Section 4, there are two distinct
modes of operation of the POWERTEC Brushless DC
motor control - Analog mode and Digital mode.

5.1 ANALOG INPUT OPERATION

The POWERTEC Brushless DC motor control is
basically a digital type of control. The analog speed
reference input capability is supplied for those who prefer
to operate the control with a speed pot or from an external
analog reference source. This input reference must be in
the form of voltage. If a current based reference source is
used, it must be converted to a voltage.
5.1.1

SPEED REFERENCE

In the analog mode, the speed of the motor is
determined by a DC voltage reference applied to TB2
terminal 10 (with respect to TB2 terminal 12). A +10VDC
reference source is available at TB2 terminal 9, referenced
to drive common (TB2 terminal 12).
A reference voltage of +10VDC will cause the motor
to run in the forward direction at full speed (as determined
by the MAX SPD pot setting - see Section 5.1.4) if terminal
14 on TB2 (the Forward/Reverse input) is open. The motor
may be reversed by applying +24VDC to terminal 14 (with
respect to TB2 terminal 12, which is a common terminal).
Zero volts input at TB2 terminal 10 will produce
zero speed. Be aware, however, that the 2000C and 3000C
will respond to inputs of more than 70 millivolts (0.07
volts), and the zero volts input must be less than this
amount, or the motor will creep because of the offset.
The reference may come from any source capable of
developing the required voltage. The input impedance at
terminal 10 on TB2 with respect to TB2 terminal 12 is
about 50 Kilohms for voltages up to +10.6VDC. (Negative
voltages will be clamped at -0.6VDC.) This high input
© copyright 1992, 1996 by Powertec Industrial
Motors

5.0 OPERATION

impedance may cause the 2000C and 3000C to respond to
electrical noise present on the reference input. Shielded
cable should be used for the reference input wiring. If long,
exposed wires are used from the reference source, it may
be necessary to use a filter on the reference input to get rid
of electrical noise.
If a 4 ->20mA current source is used, it must be
converted to +10VDC by either a fixed resistor (such as a
499 ohms, 1/2 watt, 1%) between TB2 terminal 10 and
TB2 terminal 12 (if zero and span adjustments are not
required for the process), or by an optional Process Fol-
lower Board (Part #4001-148300-XXX -- available at
additional cost from POWERTEC).
The input DC voltage reference level may be changed
at any rate desired and does not need to be removed while
the Models 2000C and 3000C are off. While the 2000C or
3000C control is off, the input is held at zero by an input
reference clamping circuit. This clamp is released as soon
as a valid run command is given and the enable is activated.
There is a minimum speed potentiometer on the
Speed Controller board (Part # 4001-141107) which may
be used to establish a minimum reference voltage when the
motor control's operator speed pot is turned to its minimum
setting. This minimum reference voltage becomes a part of
the full reference.
The value of the minimum speed potentiometer on
the Speed Controller board is 1 kilohm. With a 5kohm
speed pot, the minimum speed may be adjusted from 0 to
15% of full speed. With a 10 kilohm speed pot, the
adjustment will be only 0 to 10 % of full speed.
Figure 27: Connections for using or not using a
minimum speed pot with the Model 2000C or 3000C.
This minimum speed pot can only be effective in the
analog mode when a speed pot is used and the lower side
of the speed pot is connected to terminal 11. It does not
perform the minimum speed function when an external
reference source is used or when the Model 2000C or
3000C is used in the digital mode of operation. [A refer-
ence source for a speed pot (the high side) does not have to
come from terminal 9.]
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