Red Lion TCU - Manual (Page 18)

Valve Positioner Wiring
Units with Valve Positioner option have three output connections for
controlling the valve motor and three input connections for slidewire
feedback. The valve motor output connects to terminals labeled “Valve
Position Outputs”, terminals 1, 2 and 3. See Figure 9, Valve Positioner
Wiring for more details. Terminal 1 is the Valve motor supply common.
Terminal 2 is the Valve Close or CW output. Terminal 3 is the Valve Open or
CCW output. The valve motor common must be fused with a suitable value.
Although RC snubbers are employed inside the controller to suppress
inductive “kicks” from the motor, it may be necessary to take further action to
reduce noise effects:
1) Use Triac Output Modules wherever possible. The Triac device
significantly reduces radiated EMI (Electromagnetic Interference).
The Triac Output Module also does not suffer from mechanical wear of the
contacts.
2) Use RC snubbers directly across the valve motor.
3) Use a separate AC supply for the valve motor.
Where possible, the valve motor control outputs and the slidewire
feedback input routing should be physically separated. Noise interference
from the outputs could couple into the slidewire feedback inputs, disrupting
proper operation.
The slidewire feedback inputs connect to the terminals labeled “Slidewire
Feedback Inputs”. The terminal placement varies with each model, see the
controller label for the actual terminals. For Velocity mode valve control the
slidewire feedback inputs are not necessary.
In some cases, it may be desirable to have an independent valve position
indicator. Red Lion Controls Model IMD1 can be wired in parallel with the
slidewire input’s Wiper and Comm. terminals for this purpose. The
approximate 0 to 0.9 V signal can be scaled to indicate percent valve position.
Linear DC Output Wiring
Units with Linear DC output option have two terminals to output a 4 to 20
mA or 0 to 10 VDC signal. The type of Linear DC output is determined by the
model ordered. (See Ordering Information page 90, for available models.)
These terminals are labeled “4-20 mA (or 0-10 VDC) Analog Output Option,
Out+ and Out-”. The common of this output is isolated from thermocouple
common , but is not isolated from the Second Analog Input Option common.
For proper operation always keep these commons isolated.
Second Analog Input Wiring
Units with Second Analog Input option have two input terminals to receive
a 4 to 20 mA signal. These terminals are labeled “Second Input, 4-20 mA+ and
4-20 mA-”. Terminal placement varies with model. See unit label for actual
terminals. The common of this input is isolated from thermocouple common,
but is not isolated from the Linear DC Output common. For proper operation
always keep these commons isolated.
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Figure 9, Valve Positioner Wiring