Cutler-Hammer - Eaton Canada

AF93/IS903 Parameter Descriptions
USING THE PARAMETERS
Remote Function
Specifications
Parameter Number: 23
Mnemonic: REMOTE FUNCTION
Range of Adjustment: ÒSPEED FOLLOWERÓ or
ÒPI REGULATORÓ or
ÒANALOG LOAD LIMÓ or
ÒDIGITAL POTÓ
Run Locked?: Yes
Factory Setting: ÒSPEED FOLLOWERÓ
When your drive is in REMOTE mode, speed is
controlled by one of the these Remote Functions:
ÒSPEED FOLLOWERÓ, ÒPI REGULATORÓ,
ÒANALOG LOAD LIMÓ or ÒDIGITAL POTÓ.
A discussion about the priority interaction among
the various signals that can control the motor
speed follows the discussion of each type of
remote function.
ÒSPEED FOLLOWERÓ - You can vary the speed
setpoint using a current or voltage speed follower
input. The speed follower input can be connected
as follows:
¥ If the signal is 4-20 mA, connect it to
terminals 1 and 2.
¥ If the signal is 0-10 VDC, connect it to
terminals 2 and 3.
¥ If the signal comes from a potentiometer,
connect it to terminals 2, 3, and 4.
¥ If the signal is 0-5 VDC, and the output
impedance of the signal follower is less than
or equal to 250 ½ and can output 20 mA,
connect the signal to terminals 1 and 2.
ÒPI REGULATORÓ - You can automatically
maintain a reference setpoint using the ÒPI
REGULATORÓ option. This option incorporates a
feedback signal and reference setpoint. The
following connections are required:
Setpoint - 0-10 VDC, connect it to terminals 2
and 3 (terminal 3 is +) or connect potentiometer
to terminals 2, 3, and 4.
AF93/IS903 Instruction Manual
4-18
Feedback - 4-20 mA connected to terminals 1
and 2. A 0-5 VDC signal can also be connected
to these terminals if the output impedance of the
transducer is less than or equal to 250 ½ and it
can output 20 mA.
PI Regulator Feedback - The feedback signal is
calibrated to provide constant information on
whether the motor is actually running faster or
slower than the setpoint. If the motor is running
faster than setpoint, the drive reduces the
frequency and if the motor is running slower than
setpoint, the drive increases the frequency.
Integral and Proportional Gain - In simple
terms, the Integral Gain parameter controls how
quickly the drive responds to information
provided by the feedback signal and the
Proportional Gain parameter controls how close
to the target value the system will maintain
control. It takes some trial and error in setting
these parameters since some applications have
a natural tendency to favor tight control and
others may start to quickly oscillate around the
target speed the tighter you try to maintain
control.
PI Regulator Application Example - PI is a
closed loop control system consisting of a set
point, a process variable, and an error signal
which will control the drive output. Typical
applications include wet well level control,
temperature or pressure control, or flow rate
control.
PI control starts with a PI Setpoint adjusted by a
remote signal input, such as a potentiometer. The
drive compares the setpoint to a process variable
signal, PI Feedback, and creates an error signal.
The error signal is processed to create the speed
reference for the drive.
In the example shown in Figure 4-1, a pressure
transducer provides a 4-20 mA signal that
corresponds to the duct pressure. The drive will
control the speed of the blower to maintain the
desired duct pressure regardless of the amount of
air flow being supplied through the duct.