Woodward 2301D, Инструкция по установке и эксплуатации, Страница: 18 / 130

2301D/2301D-EC Digital Control Manual 26247
10 Woodward
Electrical Connections
All inputs and outputs are made through screwless spring-actuated terminal
blocks. For EMI reasons, it is recommend that all low-current wires be separated
from all high-current wire.
The spring clamp can be actuated by using a standard 2.5 mm or 3/32 inch flat
bladed screwdriver. The terminal blocks accept wires from 0.08–4 mm² (27–12
AWG). Two 18 AWG or three 20 AWG wires can be easily installed in each
terminal. Wires for the fixed mounted power terminals should be stripped 5–6
mm (0.22 inch) long.
Do not tin (solder) the wires that terminate at the terminal blocks. The
spring-loaded terminal blocks are designed to flatten stranded wire,
and if those strands are tinned together, the connection loses
surface area and is degraded.
Shields and Grounding
An individual shield termination is provided at the terminal block for each of the
signals requiring shielding. All of these inputs should be wired using shielded,
twisted-pair wiring. The exposed wire length beyond the shield should be limited
to one 25 mm (1 inch). Relay outputs, contact inputs, and power supply wiring do
not normally require shielding, but can be shielded if desired.
The 2301D is designed for shield termination to earth ground at the control. If
intervening terminal blocks are used in routing a signal, the shield should be
continued through the terminal block. If shield grounding is desired at the
terminal block, it should be ac coupled to earth. All other shield terminations
except at the control should be ac coupled to earth through a capacitor. A 1000
pF, 500 V capacitor is sufficient. The intent is to provide a low impedance path to
earth for the shield at frequencies of 150 kHz and up. Multiple direct connections
of a shield to earth risk high levels of current to flow within the shield (exception,
see note below on cabinet installations).
Shields can be grounded at both ends (2301D and load) if the cable length is
sufficiently short (i.e. within a cabinet) to prevent ground loop current in the
shield.
Cabinet Installations: If the 2301D is installed in a cabinet, shielded
I/O can be terminated directly to the cabinet (earth ground) at the
entry to the cabinet, as well as at the control.
For EMC reasons, it is recommend that all low-current wires be
separated from all high-current wires. Input Power ground terminal
should also be wired to earth ground.