Operator`s manual

SECTION 14. INSTALLATION AND MAINTENANCE
14-2
14.2 POWER REQUIREMENTS
The 21X operates at a nominal 12V DC. Below
9.6 or above 16 volts the 21X does not operate
properly.
The 21X is diode protected against accidental
reversal of the positive and ground leads from
the battery. Input voltages in excess of 18V
may damage the 21X and/or power supply. A
transzorb provides transient protection by
limiting voltage at approximately 20V.
System operating time for the batteries can be
determined by dividing the battery capacity
(amp-hours) by the average system current
drain. The 21X draws 1.0 mA in the quiescent
state, 25 mA while processing, and 60 mA
during an analog measurement; the length of
operating time for each datalogger instruction is
listed in Section 3. Typical current requirements
for common 21X peripherals are given in Table
14.2-1.
FIGURE 14.3-1. 21X Battery Pack and Panel