Campbell Scientific CR1000KD CR800 and CR850 Measurement and Control Systems - Page 83
CR800 Power Requirement, 4.2 Calculating Power Consumption, 4.3 Power Supplies, 4.4 Vehicle
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Section 7. Installation Power supplies available from Campbell Scientific can be reviewed in the appendix Power Supplies (p. 542), or at www.campbellsci.com. Contact a Campbell Scientific application engineer if assistance in selecting a power supply is needed, particularly with applications in extreme environments. 7.4.1 CR800 Power Requirement The CR800 operates on dc voltage ranging from 9.6 to 16 Vdc. It is internally protected against accidental polarity reversal. A transient voltage suppressor (TVS) diode on the 12-Vdc power input terminal (p. 35) provides transient protection by clamping voltages in the range of 19 to 21 V. Sustained input voltages in excess of 19 V can damage the TVS diode. Caution The 12V and SW12 terminals on the wiring panel are not regulated by the CR800; they are at the same voltage levels as the CR800 primary power supply. When using the CR800 wiring panel to source power to other 12-Vdc devices, be sure the power supply regulates the voltage within the range specified by the manufacturer of the connected device. 7.4.2 Calculating Power Consumption Read More! Power Requirements (p. 64). System operating time for batteries can be determined by dividing the battery capacity (ampere-hours) by the average system current drain (amperes). The CR800 typically has a quiescent current draw of 0.5 mA (with display off), 0.6 mA with a 1-Hz sample rate, and >10 mA with a 100-Hz sample rate. With the external keyboard / display on, an additional 7 mA is added to the current drain while enabling the backlight for the display adds 100 mA to the current drain. 7.4.3 Power Supplies The appendix Power Supplies (p. 542) lists external power supplies available from Campbell Scientific, including alkaline and solar options. More information is available in manual or brochure form at www.campbellsci.com. 7.4.3.1 External Batteries When connecting external power to the CR800, remove the green POWER IN connector from the CR800 face. Insert the positive 12-Vdc lead into green connector terminal 12V. Insert the ground lead in green connector terminal G. Re-seat the green connector into the CR800. The CR800 is internally protected against reversed external-power polarity. Should this occur, correct the wire connections. 7.4.4 Vehicle Power Connections If a CR800 is powered by a motor-vehicle power supply, a second power supply may be needed. When starting the motor of the vehicle, battery voltage often drops below 9.6 Vdc. This causes the CR800 to stop measurements until the voltage again equals or exceeds 9.6 Vdc. A second supply can be provided to prevent measurement lapses during vehicle starting. The figure Connecting CR800 to Vehicle Power Supply (p. 84) illustrates how a second power supply 83