7
OVERVIEW
Pem-Tech model PT902M is a microprocessor based single channel monitor
that utilizes the latest digital design techniques in instrumentation. The
monitor uses an 8-bit high speed RISC processor with a highly accurate analog
to digital logic. The control module receives signal from the remote gas
transmitter, displays the gas concentration, and generates 4-20mA analog
output. The discrete outputs from 4 alarm relays can be used to activate
external alarm devices. Each control module is connected to a common
24VDC supply at the back of the 19” Rack assembly. The module provides
power to the remote sensor & transmitters via 2Amp miniature fuse.
Standard features are:
•
Displays current gas concentration on two (2) Digit Bright LED display .
•
Provides a 4-20mA output.
•
Low, High, & High-High fully programmable alarm relay contacts.
•
Alarms programmable via switches on the front panel
•
Sensor Malfunction relay contact.
•
Visual alarm indicators on the front panel.
•
Alarm RESET and BYPASS switch.
•
RS485 Serial Communication for Remote data display
•
Master Alarm Reset connection for Remote alarm Reset Switch.
Programmable Relays
Each control module has three (3) programmable relays for Low, High, and
High-High alarms. The alarm relay set points can be programmed via
pushbutton switch provided on the front panel. Sensor and alarm
terminations are provided on the rear of the 19” Rack assembly. A common
terminal is also provided for sensor malfunction (or fault). This terminal is
common to the Fail relays on all the control modules in the system. The
terminal can, therefore, be used as dry contact for a local audible alarm. In
addition jumper blocks are also provided to common all the relays on the
control modules in order to use an auxiliary relays.
For further details refer to section on Programming alarm Relays later in this
manual.
