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Speed Controls
When shipped from the factory all 709 Series controls are config-
ured to de-energize the motor when the dc input level falls below
2.0 VDC or 4 mA. A maximum speed setting of line voltage less
10% is also configured. Performance may be modified by calibrat-
ing the following control potentiometers.
POTENTIOMETER DEFINITIONS
Cal Pot R5
Used to simulate a 2-10 VDC input internally to the 709 Series
control. (For mA calibration values, multiply VDC by 2)
Cutoff Pot R11
Used to set a given input level that causes the control to "turn off"
the motor when the input signal has dropped below this level.
Maximum Speed Pot R13
Used to adjust the maximum motor speed when the full input
signal (10 VDC or 20 mA) level is applied.
Minimum Speed Pot R15
Used to adjust the minimum motor speed when the input signal
level of 2 VDC or 4 mA is applied.
Controller Setup
When shipped from the factory all 709 series controls have
received the following standard calibration.
• The minimum motor speed setting is adjusted to approximately
400 RPM for a sleeve bearing motor.
• The maximum motor speed setting is adjusted to provide the
motor with approximately line voltage minus 10% as full speed.
• The 709 Series control has a "cutoff" set to de-energize the
motor when the DC input to the control drops below a 2 volt
level.
• Models equipped with a PI Interface have the PI Interface
configured for "DA" operation by default.
These setting may be adequate for most installations. If it is deter-
mined that a re-calibration is required due to the particulars of
the installation, follow all steps of the re-calibration procedure as
listed in the "Re-Calibration Procedure" section below.
Test Point (TP1) Measurements
Monitor TP1 of the 709series control with respect to circuit
ground using a DVM. The Cal Pot voltage used during calibration
(to simulate a 2-10 VDC input) is monitored here.
Motor Volts Measurements
It is preferable to calibrate the control while monitoring voltage
present across the motor windings.
Re-Calibration Procedure
Initial Potentiometer Settings
• Cutoff Pot at full ccw (minimum) position.
• Cal Pot at full ccw (minimum) position.
• Minimum Speed Pot at approximately center position.
• Maximum Speed Pot at approximately center position.
Note: If PI is installed, ensure mode select is in "RA" position with
the set point pot adjusted to full ccw position.
CALIBRATION PROCEDURE
1. Disconnect 2-10 VDC or 4-20 mA input from 709 controller.
2. Power up motor & 709 controller.
3. Adjust Cal Pot R5 (cw rotation) until 10.0 VDC is read on
TP1.
4. Adjust the Maximum Speed Pot R13 (cw or ccw as required) to
achieve desired maximum motor voltage and RPM.
a) HCC recommends that a maximum motor voltage setting
equal to line voltage minus 10% be used to obtain the most
linear response for use of the full rpm requirement.
For a 120 VAC motor adjust for 108 VAC across motor.
For a 240 VAC motor adjust for 216 VAC across motor.
b) A correctly calibrated motor will yield the most linear
response curve of motor performance.
c) A motor voltage setting equal to line voltage minus 10 VAC is
the maximum level recommended at full speed.
5. Adjust Cal Pot R5 (ccw rotation) until 2.0 VDC is read on
TP1. The motor may de-energize at this time until your
may
may de-energize at this time until your
minimum speed has been properly set.
6. Adjust the Minimum Speed Pot R15 (cw or ccw as required) to
achieve desired minimum motor voltage and RPM.
a) HCC recommends not less than 200 rpm for ball bearing,
and 400 rpm for sleeve bearing motors.
b) The Minimum Speed Pot and Maximum Speed Pot will
interact with each other, repeat steps 3 through 6 as required.
7. For a continuous flow application, no further adjustment is
required. Stop the calibration procedure at this point. Leave the
Cal Pot R5 in its current position at 2.0 VDC.
a) The motor will run at this speed until the external input
signal indicates demand, forcing a change in motor speed.
b) For a switching application that requires the control to cutoff,
proceed with calibration steps 8 & 9 below.
8. Adjust cutoff pot R11 (cw rotation) slowly until motor de-
energizes.
a) This sets the point a motor will "turn off " as the input signal
decreases to the set point (currently simulated by the Cal Pot
setting). The motor will turn ON again at approximately this
cutoff level + 0.3 VDC.
b) The minimum required cutoff input level is 2.0 VDC.
The maximum available cutoff input level is 6.0 VDC.
9. Adjust Cal Pot R5 back to full ccw position. This will allow the
unit to run the fan in a "cutoff" mode which de-energizes the
motor when the input signal indicates no demand.
RE-CALIBRATION COMPLETED
Note: Important
Note: Important - verify that PI mode jumper is returned to
Note: Important - verify that PI mode jumper is returned to
proper position for your application.
Final Controller Installation
De-energize all system components.
Insure all wiring and connections are in compliance with appli-
cable state and local codes.
Reconnect the signal inputs to the controller, or the PI interface
card, if used.
Re-install long top cover, securing it with (4) self-tapping screws.
Installation Completed
2
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