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MODEL 2746–2747
motor controls are exceptionally rugged, full wave, unidirectional
(single quadrant) units that control motor speed and torque of shunt
wound and permanent magnet DC motors. These two models are equivalent
except that Model 2746 has an isolated speed command input, while
Model 2747 uses an external 5KO speed potentiometer.
Both models are fully adjustable, industrial grade controls packaged
in compact, low cost frames which make them ideal for OEM applications
that require unidirectional control with isolated or remote speed
command inputs.
These controls are designed to be easily interfaced to either analog
or digital low level circuitry, and input signals are isolated from
motor and power line with 1500 VDC minimum isolation voltage, reducing
the possibility of grounding, noise or safety problems.
ANALOG INPUTS: Motor speed is proportional to the amplitude
of the isolated input signal (see figure). The equivalent circuit
of the isolated speed input port is 150O in series with diode voltage
drop of 1.1 VDC. The input/output curve is approximately linear,
with a threshold at 1.3 VDC. This characteristic is suitable for
precise speed control within a closed loop system where speed is
sensed and and controlled externally, or for application requiring
isolation at low cost without high input/output precision.
DIGITAL INPUTS: The input port may be pulsewidth modulated
with 1–100 kHz TTL level signal to control motor speed. Input
pulsewidth vs. motor voltage is linear, and more repeatable in digital
mode than analog mode.
An isolated inhibit signal is provided. The motor operates normally
when this signal is de-energized. When energized, the motor output
is inhibited. The equivalent circuit of the inhibit input is 1000O
in series with a diode voltage drop of 1.1 VDC.
Adjustment controls include minimum speed, maximum speed, current/torque
limit, IR compensation (for adjustment of speed regulation), acceleration
and deceleration. Full load rated horsepower ranging from 1/30th
to 2 HP is user settable by easily accessed dip switches.
These units incorporate thyristor phase angle control and operate
from nominal 115 or 230 VAC, 50/60 Hz lines. When used with a 115
VAC line, 90 VDC motors are driven. A field voltage supply producing
either 50 or 100 VDC is incorporated for shunt field motors (100
and 200 VDC for 230 VAC inputs).
These POWR UPS motor controls are of high quality open frame construction,
and mounting holes are provided for either bottom or edge mounting.
A removable barrier block is used for input and output connections,
allowing rapid field rewiring.
An optional perforated metal cover (2746 COVER) is also available.
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