Campbell CR800 Specifications download pdf (Page 53)

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Section 1. Installation and Maintenance

1.1 Protection from the Environment

The normal environmental variables of concern are temperature and moisture.

The standard CR800 is designed to operate reliably from -25 to +50°C (-40°C

to +85°C, optional) in noncondensing humidity. When humidity tolerances are

exceeded, damage to IC chips, microprocessor failure, and/or measurement

inaccuracies due to condensation on the PC board may result. Effective

humidity control is the responsibility of the user.

Internal moisture is eliminated by sealing the module at the factory with a

packet of silica gel inside. The desiccant is replaced whenever the CR800 is

repaired at Campbell Scientific. The module should not be opened by the user

except to replace the lithium coin cell providing back up power to the clock

and SRAM. Repeated disassembly/ assembly of the CR800 will degrade the

seal, leading to potential moisture problems. Extra desiccant should also be

placed in the enclosure to prevent corrosion on the Wiring Panel terminals and

CR800/Wiring Panel connections.

Campbell Scientific offers environmental enclosures for housing a CR800 and

peripherals. The fiberglass enclosures are classified as NEMA 4X (watertight,

dust-tight, corrosion-resistant, indoor and outdoor use). A 1.25" diameter

entry/exit port is located at the bottom of the enclosure for routing cables and

wires. The enclosure door can be fastened with the hasp for easy access, or

with the two supplied screws for more permanent applications. The white

plastic inserts at the corners of the enclosure must be removed to insert the

screws. The enclosures are white for reflecting solar radiation, thus reducing

the internal enclosure temperature.

1.2 Power Requirements

The CR800 operates at a nominal 12 VDC. Below 9.6 V or above 16 volts the

CR800 does not operate properly.

The CR800 is diode protected against accidental reversal of the positive and

ground leads from the battery. Input voltages in excess of 18 V may damage

the CR800 and/or power supply. A transzorb provides transient protection by

limiting voltage at approximately 20 V.

System operating time for the batteries can be determined by dividing the battery

capacity (amp-hours) by the average system current drain. The CR800 typically

draws 0.5 mA in the sleep state (with display off), 0.6 mA with a 1 Hz sample

rate, and >10 mA with a 100 Hz sample rate.

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Campbell CR800 Specifications Page 53