Instruction Manual

Instruction Manual

D103557X012

Wiring Practices

January 2015

Auxiliary Terminal Wiring Length Guidelines

The Auxiliary Input Terminals of a DVC6200 SIS can be used with an LCP100 local control panel or a locally‐mounted

switch for initiating a partial stroke test. Some applications require that the switch or local control panel be installed

remotely from the DVC6200 SIS.

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 100,000 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 100,000 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 = 100,000pF /(26pF/ft) =3846 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 = 100,000pF /(97pF/ft) = 1030 ft

The AUX switch input passes less than 1 mA through the switch contacts, and uses less than 5 V, 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.