Chapter 1. Installation
1-29
DigitalFlow™ GC868 Startup Guide (1 and 2-Channel)
Figure 1-37: Network Connections - Standard Option Interior
1.8.5
Wiring an Alarms
Option Card
The Model GC868 flowmeter can accommodate up to 4 alarm option cards. Each
alarm option card includes three
Form C relays
(designated as A, B and C).
The alarm relays on the option card are available in two types:
•
general purpose
•
hermetically sealed for Class I, Division 2 hazardous areas.
The maximum electrical ratings for the relays are listed in Chapter 4,
Specifications
.
Each of the three alarm relays can be wired either as
Normally Open
(NO) or
Normally Closed
(NC).
In setting up an alarm relay, it may be wired for either
conventional
or
fail-safe
operation. In fail-safe mode, the alarm relay is constantly energized, except when it
is triggered or a power failure or other interruption occurs. See Figure 1-38 below for
the operation of an alarm relay in both conventional and fail-safe mode.
Connect the two wires required for each alarm relay in accordance with the pin
number assignments shown in Figure 1-42 on page 1-43.
1
9
J8
1
9
J9