CM4 Four-Point Continuous Monitor
CM4 Technical Manual
1-7
2 alarms at any point
• A Maintenance fault relay (RY8) which indicates the CM4 needs
attention but is continuing to monitor
• An Instrument fault relay (RY10) which indicates the CM4 is
unable to monitor one or more points
In addition, the I/O panel includes:
• Terminals for the current loop options, which produce a 4-20
mA output signal in direct variation to the gas concentration
at each point
• Terminals for the remote reset option, which permit resetting
of faults and alarms for specific points
1.5.2 Power Connection
Connect AC power to the CM4 at the rear panel. The power switch is
located above the power line connection.
1.5.3 Optional Serial Output
Install the optional DB9 (nine-pin) serial data and printer connectors
on the back panel.
1.6 Alarms
The CM4 has alarms that:
• Warn of Level 1 or Level 2 low or high concentrations of the
monitored gas
• Trigger relays to external devices
describes wiring.
describes operation modes and basic operating procedures.
1.6.1 General and Point Gas Alarms
The factory default setting for the Level 1 alarm is the threshold limit
value (TLV) of the monitored gas. The default setting for the Level 2
alarm is two times the TLV. Level 1 and 2 alarms can be factory set
to 1/2 TLV and 1 TLV by specifying part number 1874-0330.
You can also set individual alarm levels for each sample point. Separate
alarm levels for each point provide added protection in critical locations
and allow you to customize the settings to meet the specific needs
of your site.
1.6.2 Activating an Alarm
When the CM4 detects a gas concentration that exceeds a
programmed alarm level, it activates a series of signals. The CM4
continues monitoring during an alarm condition.
NOTE:
When a Level 2 alarm activates, the Level 1 alarm always activates.
•
Alarm LEDs indicate Level 1 and Level 2 alarms for the
appropriate point
•
The gas alarm relay contacts activate for the appropriate point
•
The general alarm contacts activate
•
The display continues to show the point number, gas type and
gas concentrations
•
The instrument generates the appropriate current loop signal
(2-20 mA/4-20 mA) and an audible tone
•
Alarm information is sent to the printer for printing (if enabled)
•
Alarm data (most recent 16 alarm events) is stored in memory
•
Alarm information is made available over the optional digital
network port
珠海司福斯特科技有限公司
www.safedtech.com
