PCC-IV Instruction Manual (rev. 0.2)
Page 2-4
Section 2 - Installation
Wiring Overview
WARNING
The PCC-IV is commonly used to control potentially dangerous combustion and chemical processes. VERIFY THAT
THE PROCESS BEING CONTROLLED HAS BEEN SAFELY SECURED, ISOLATED, OR BYPASSED (AS
REQUIRED BY THE SITE CONDITIONS) BEFORE REMOVING POWER FROM THE PCC-IV CONTROLLER.
FAILURE TO DO SO CAN RESULT IN EQUIPMENT DAMAGE, INJURY, OR DEATH.
WARNING
It is very common to have multiple sources of power among the wires connected to a PCC-IV. VERIFY THAT ALL
SOURCES OF POWER HAVE BEEN DISCONNECTED BEFORE WORKING ON WIRING. FAILURE TO DO SO
CAN RESULT IN INJURY OR DEATH.
All Panel and Field wiring should conform to National and Local Electrical Codes. Typically, NEC (National Electric
Code) applies to field wiring; while NFPA 79 and UL508 applies to Industrial Control Panel wiring.
120 Vac Ground
Connect the incoming AC Power Ground (i.e.
“Green Wire” Ground) to the screw and lug marked “GROUND” inside
the rear of the case near the bottom of the terminal strips. AC Ground is not connected to
DC Common. See “DC
Commons and AC Neutrals” on page 2-20.
Terminal Blocks
(See Field Wiring Label below)
All field wiring terminals are separable and plug-in to the PC board. This allows rapid board-level replacement
without disconnecting individual field wires. Verify that terminals are inserted properly before applying power.
The AC terminals on the CPU board are numbered 1L to 8L and 1U to 8U. The terminals are arranged in two rows
of eight
. “L” refers to the lower row, while “U” refers to the upper row.
Terminals 1L to 8L, 1U to 8U, and 29 to 33 accept 24-12 ga. wire and should be tightened to 4.5 in-lb.
Terminals 1 to 28, and 40 to 51 accept 22-14 ga. wire and should be tightened to 2.2 in-lb.
Wire Type
All wiring (AC, DC, and shielded cable) should be copper, stranded, 150 V min., and 60
C minimum.
Shielded Cable
All 4-20 mA / 0-5 Vdc input and output wiring and 24 Vdc power supply wiring should be 22-gauge minimum, 85%
shield (min.) and have twisted pairs (Belden 8737 or equal). 100% foil shielding is preferable, if available.
The shields of all 4-20 mA / 0-5 Vdc cables should be connected at one end only, as shown on the drawings that
follow. Generally, the shield is connected to the DC common of the Power Supply that is powering the signal. All
shield foils, and shield wires should be insulated (taped or heat shrink) to prevent accidental connection to earth or
power ground. Shields connected at both ends, or unintentional second grounds can add extra noise to a signal
instead of reducing noise. To prevent noise pick-up, shielded cables should never be run in conduits or trays with
AC wiring (any voltage). Ignition transformer and variable frequency drive AC wiring is particularly noisy and should
be kept separated from all DC signal wiring.
24 Vdc Redundant Power Input Terminals
An external 24 Vdc power supply powers the PCC-IV. The PCC-IV CPU board has dual, diode isolated, 24 Vdc
power input terminals. 24 Vdc only needs to be connected to one of the inputs. A second, redundant 24 Vdc power
supply can be connected to the other 24 Vdc input terminals, if desired, but it is not required. The shield of the 24
Vdc power supply should be connected to the power supply negative terminal; tape off the shield at the PCC-IV.
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