-7-
6.3 (continued)
D. In the case of a field conversion, where sensors have previously been used with Murphy
tattletales, it is recommended that the sensors be checked frequently when the DE system
is first put into use. Sensor contacts may be burned or pitted from past exposure to
ignition system primary voltage. It is advisable to replace such sensors.
E. If it becomes necessary to check sensor switch to panel wiring with an ohmmeter or other
checker, first DISCONNECT the plug-in terminal strips from the Terminal Module.
Applying voltage to the DE-2500 system through the sensor leads may damage the
device. The area should be tested as non-hazardous before such testing commences.
ANALOG SENSOR WIRING - For each analog monitored point, inputs 30-37 and 40-45, select
a transducer - either an Altronic pressure or temperature transducer listed above or one that
outputs a signal in the range of 0 to 5 Vdc or 0 to 25 mA. Mount as described above. Use
cable assembly 693008-x or similar to wire transducer to the Terminal Module. An internal 5
volt sensor supply (500 mA. max.) is available to power the Altronic transducers; see wiring
diagrams. If the 5 volt sensor supply exits the panel, it must be fused with a 0.5 ampere fuse.
If 24Vdc powered sensors are used, the 24 volt supply to them must be fused appropriately.
Take care not to damage the insulation when installing and take precautions against later
damage from vibration, abrasion, or liquids in conduits. In addition, it is essential that the
following practices be adhered to:
A. Never run sensor wires in the same conduit with ignition wiring or other high energy wiring
such as AC line power.
B. Keep secondary wires to spark plugs and other high voltage wiring at least eight inches
(200mm) away from sensor and sensor wiring.
6.4 THERMOCOUPLES AND THERMOCOUPLE EXTENSION WIRE - On DE-2500 units serial
numbers 1525 or above, the direct measurement of thermocouples can be selected. Grounded
or ungrounded type J or K thermocouples may be used. Use thermocouple extension wire of
the same type as the thermocouple probe to connect to the terminal module. Use stranded
thermocouple wire having a moisture-resistant insulation such as PVC; for higher ambient
temperatures, Teflon or B-fibre insulated thermocouple wire is recommended. To ensure that
an accurate signal is transmitted to the device, avoid any added junctions, splices and contact
with other metals. All unused inputs must be shorted with a short jumper wire between
terminals. Take care not to damage the insulation when installing and take precautions against
later damage from vibration, abrasion, or liquids in conduits. In addition, it is essential that the
following practices be adhered to:
A. Never run sensor wires in the same conduit with ignition wiring or other high energy wiring
such as AC line power.
B. Keep secondary wires to spark plugs and other high voltage wiring at least eight inches
(200mm) away from sensor and sensor wiring.
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