Spectrum Controls 1762sc-IF8U - Manual (Page 17)

Chapter 2: Installation and Wiring 2-7
User's Manual Pub. 0300243‐02 Rev. B
!
Attention
EXPLOSION HAZARD
 In Class I, Division 2 applications, the bus connector must be
fully seated and the bus connector cover must be snapped in
place.
 In Class I, Division 2 applications, all modules must be
mounted in direct contact with each other as shown on page 2-
5. If DIN rail mounting is used, an end stop must be installed
ahead of the controller and after the last 1762 I/O module.
Section 2.6
Field Wiring
Connections
Consider the following when wiring your system:
General
 Power and input wiring must be in accordance with Class 1, Division 2 wiring
methods, Article 501-4(b) of the National Electric Code, NFPA 70, and in
accordance with the authority having jurisdiction.
 Channels are isolated from one another by ±10 Vdc maximum.
 If multiple power supplies are used with analog millivolt inputs, the power
supply commons must be connected.
Terminal Block
 Do not tamper with or remove the CJC sensor on the terminal block. Removal of
the sensor reduces accuracy.
 For millivolt sensors, use Belden 8761 shielded, twisted-pair wire (or
equivalent) to ensure proper operation and high immunity to electrical noise.
 For a thermocouple, use the shielded, twisted-pair thermocouple extension lead
wires specified by the thermocouple manufacturer. Using the incorrect type of
thermocouple extension wire or not following the correct polarity will cause
invalid readings.
 To ensure optimum accuracy, limit overall cable impedance by keeping a cable
as short as possible. Locate the module as close to input devices as the
application permits.
Grounding
!
Attention
The possibility exists that a grounded or exposed thermocouple can
become shorted to a potential greater than that of the thermocouple
itself. Due to possible shock hazard, take care when wiring grounded or
exposed thermocouples.
!
Attention
USE SUPPLY WIRES SUITALE FOR 20°C ABOVE SURROUNDING
AMBIENT