Fisher FIELDVUE DVC6200 Instruction Manual page 92

Viewing Device Variables and Diagnostics
May 2013
Auxiliary Terminal Wiring Length Guidelines
The Auxiliary Input Terminals of a DVC6200 with instrument level ODV can be used with a locally‐mounted switch for
initiating a partial stroke test. Some applications require that the partial stroke test be initiated from a remote
location.
The length for wiring connected to the Auxiliary Input Terminals is limited by capacitance. For proper operation of the
Auxiliary Input Terminals capacitance should not exceed 18000 pF. As with all control signal wiring, good wiring
practices should be observed to minimize adverse effect of electrical noise on the Aux Switch function.
Example Calculation: Capacitance per foot or per meter is required to calculate the length of wire that may be
connected to the Aux switch input. The wire should not exceed the capacitance limit of 18000 pF. Typically the wire
manufacturer supplies a data sheet which provides all of the electrical properties of the wire. The pertinent parameter
is the highest possible capacitance. If shielded wire is used, the appropriate number is the "Conductor to Other
Conductor & Shield" value.
Example — 18AWG Unshielded Audio, Control and Instrumentation Cable
Manufacturer's specifications include:
Nom. Capacitance Conductor to Conductor @ 1 KHz: 26 pF/ft
Nom. Conductor DC Resistance @ 20 Deg. C: 5.96 Ohms/1000 ft
Max. Operating Voltage - UL 200 V RMS (PLTC, CMG),150 V RMS (ITC)
Allowable Length with this cable = 18000pF /(26pF/ft) = 692 ft
Example — 18AWG Shielded Audio, Control and Instrumentation Cable
Manufacturer's specifications include:
Nom. Characteristic Impedance: 29 Ohms
Nom. Inductance: .15 μH/ft
Nom. Capacitance Conductor to Conductor @ 1 KHz: 51 pF/ft
Nom. Cap. Cond. to other Cond. & Shield @ 1 KHz 97 pF/ft
Allowable Length with this cable = 18000pF /(97pF/ft) = 185 ft
The AUX switch input passes less than 1 mA through the switch contacts, and uses less than 5V, therefore, neither the
resistance nor the voltage rating of the cable are critical. Ensure that switch contact corrosion is prevented. It is
generally advisable that the switch have gold‐plated or sealed contacts.
Field Communicator
1. Connect the Field Communicator to the LOOP terminals on the digital valve controller.
2. Turn on the Field Communicator.
3. From the Online menu, select Service Tools > Partial Stroke Test.
4. Select either Standard (10%) or Custom. With the Custom Stroke Test, the stroke may be entered up to 30% with
configurable stroking speed and pause time.
5. The currently configured Stroke, Stroking Speed, and Pause Time is displayed. Choose "Yes" to run the test using
these values. Choose "No" to modify the values. The default value for Stroke Speed is 0.25%/second.
6. The valve begins to move and the actual travel reported by the digital valve controller is displayed on the Field
Communicator.
7. Once the valve has reached the endpoint, check that the valve has reached the desired set point. The valve should
return to its original position.
For information on configuring the Partial Stroke Test, see Partial Stroke Variables in the Detailed Setup section.
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Instruction Manual
D103409X012