CM4 Four-Point Continuous Monitor
CM4 Technical Manual
3-13
3.10.3 Wiring Guidelines
To wire the alarm relays:
• Use shielded cable or conduit. See
cable information.
CAUTION
Failure to replace and retighten hardware after servicing can
adversely affect instrument performance and EMC compliance. Make
certain all fasteners are reinstalled and firmly tightened. This will
ensure a proper ground.
• Connect grounds to stud at lower left corner of the I/O panel.
See
Figure 3-11
• Use #8 hardware provided
• Use a single, solid or stranded wire (not exceeding 14 gauge)
per terminal block connection
• Do not switch DC current with the relay contact unless you are
using counter electromotive force (CEMF) protection such as
a suppression diode
• Do not use the CM4 power supply for external alarm power
IMPORTANT:
Make sure all connections comply with applicable RFI/EMI standards.
1
RY1
LEVEL 1
RY2
LEVEL 2
RY4
2
RY3
3
RY5
4
RY7
GENERAL ALARMS
NC C NO
NC C NO
NC C NO
NC C NO
NC C NO
NC C NO
PT.1
PT.2
PT.3
PT.4
TB
18
TB
17
TB
16
TB
15
TB20
• 2A 125 VAC MAX.
CONT
ACT RA
TING
• FUSES BELOW FLAPS
TB19
LEVEL 1 POINT ALARMS
WARNING
EXTERNALLY APPLIED
VO
LTAGES MAY BE PRESENT AT ALARM TERMINAL BLOCK
WITH
INSTRUMENT DISCONNECTED. DISCONNECT AT SOURCE PRIOR
TO
SERVICING.
REFER
TO
USER MANUAL
1
RY9
2
RY11
3
RY13
4
RY14
CAUTION
REPLACE FUSES WITH SAME
TYPE AND RATING SPECIFIED
LEVEL 2 POINT ALARMS
REMOTE INPUTS
NO C NC
NO C NC
NO C NC
NO C NC
NO C NC
NO C NC
NO C NC
NO C NC
PT.
1
2
3
4
CURRENT LOOP
MAINTENANCE
RY8
FAULT
RY10
WATCH DOG
RY12
RY6
N.O.
SW.
INSTRUMENT STATUS
!
!
!
Ground Lug
3.11 Wiring Optional Current Loop (4-20 mA Output)
Each current loop output produces a current which varies linearly
from 4 to 20 mA as the concentration of gas varies from zero to a
user-programmable full scale concentration. The gas concentration
for 20 mA full scale defaults to the full scale of the gas, but can be
configured lower.
Furthermore, the CM4 can be configured lower to reduce these output
currents to 2 mA if certain faults occur. These outputs will drop to zero
mA after a power failure.
The current loop connection points are located on the I/O Panel.
The impedance range of the analog output is 100-800 ohms.
All wiring should follow the wiring guidelines described in Wiring
Guidelines (Section 3.10.3).
Figure 3-11: I/O Panel Connections
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