Martel Electronics 235 - Manual (Page 63)

The LPS is designed to turn itself ON and OFF automatically, based on
current demand. When a series loop exists at the LPS Loop Power jacks
calling for .5 milliamps or greater the LPS will automatically turn ON.
Open the loop and power down occurs. This allows for maximum
battery life by not allowing the unit to be left in the ON mode
accidentally.
The LPS can be used with or without the calibrator. When the test
leads are connected from the LPS Loop Power connections to a device
requiring power, the LPS automatically turns itself ON and provides
24VDC. Breaking the connections causes the LPS to automatically turn
itself OFF, preventing needless battery drain.
To use the calibrator with the LPS, simply plug the special connector
provided with the LPS from the plug marked “To mA Input” on the LPS
to the milliamp input terminals on the calibrator. This automatically
puts the calibrator in series with the 4 to 20 milliamp loop. Plug the
test leads provided with the calibrator into the jacks marked “Loop
Power” on the LPS and connect them to the instrument under test,
with proper polarity (+ to + / - to -).
The batteries of the LPS can be checked by plugging the same special
cable provided with the LPS from the plug marked “Battery Charger” on
the LPS, to the V input jacks on the calibrator. When voltage is selected
on the keypad, the LPS battery voltage will be displayed on the
calibrator.
The LPS battery voltage should be between 10.6 and 9.2 volts. When
the voltage falls below 8.8 volts, the LPS will automatically turn itself
OFF to prevent damage to the batteries due to possible cell reversal.
Output Functions
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