3.8
Ground the transmitter
The transmitter operates with the housing grounded or floating. Floating systems,
however, can cause extra noise that may affect many types of readout devices. If the signal
appears noisy or erratic, grounding at a single point may solve the problem. Ground the
electronics enclosure in accordance with local and national installation codes. Ground the
electronics using the internal or external case grounding terminal.
3.9
External alarm device electrical connections
The discrete output of the transmitter (Models 928XSS01 and 928UTX01) can trigger an
optional, customer-supplied external alarm device.
Note
The transmitter cannot power external devices. It acts as a switch that closes the power
circuit of a connected external device when activated by a gas concentration threshold if
configured to do so.
You can configure an external power supply and alert device to issue a local alarm when
the detected gas concentration level exceeds the specified high concentration threshold.
You can configure the local alarm to latch the alarm output until the alarm is manually
cleared or query the device to detect whether this option is installed. Examples of alarm
mechanism options include:
•
Audible alarm
•
Visual alarm (for example, a flashing light)
•
Initiate action (for example, close valves, initiate facility evacuation, call emergency
services)
WARNING
Alarm
If installing an optional, customer-supplied external alarm device, verify proper
function.
Verify that gas concentrations in the area have dissipated to a safe level before clearing
local or digital alarms.
When connecting an external device to the monitor's discrete output in a hazardous
area, ensure that the external device is installed in accordance with Intrinsically Safe or
non-incendive field wiring practices.
The transmitter does not need to be connected to a wireless network for the external
alarm device to function. However, the low battery, no measurement, or sensor failure
alerts will not be available.
There are two possible connection methods for the external alarm device:
•
Four-wire: This connection method (most common) uses a set of two wires for an IS
input power supply. Another set of two input wires is used for a separate IS alarm
mechanism.
•
Two-wire: This connection method combines an IS power source, such as an internal
battery, and alarm device into one package.
Reference Manual
Install
00809-0100-4928
September 2019
Rosemount 928
115
Summary of Contents for Rosemount 928
Page 1: ...Reference Manual 00809 0100 4928 Rev AE September 2019 Rosemount 928 Wireless Gas Monitor ...
Page 4: ...4 ...
Page 8: ...Contents Reference Manual September 2019 00809 0100 4928 viii Emerson com Rosemount ...
Page 106: ...Configuration Reference Manual September 2019 00809 0100 4928 106 Emerson com Rosemount ...
Page 178: ...Troubleshooting Reference Manual September 2019 00809 0100 4928 178 Emerson com Rosemount ...