Campbell CR3000 Micrologger, Руководство оператора

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Section 8. Operation
424
8.2 Switched-Voltage Output — Details
Related Topics:
• Switched Voltage Output — Specifications
• Switched Voltage Output — Overview
(p. 62)
• Switched Voltage Output — Details
(p. 424)
• Current Source and Sink Limits
(p. 424)
• PLC Control — Overview
(p. 91)
• PLC Control Modules — Overview
(p. 430)
• PLC Control Modules — Lists
(p. 607)
The CR3000 wiring panel is a convenient power distribution device for powering
sensors and peripherals that require a 5 Vdc, or 12 Vdc source. It has two
continuous 12 Vdc terminals (12V), two program-controlled, switched, 12 Vdc
terminals (SW12), and one continuous 5 Vdc terminal (5V). SW12, 12V, and
5V terminals limit current internally for protection against accidental short
circuits. Voltage on the 12V and SW12 terminals can vary widely and will
fluctuate with the dc supply used to power the CR3000, so be careful to match the
datalogger power supply to the requirements of the sensors. The 5V terminal is
internally regulated to within ±4%, which is good regulation as a power source,
but typically not adequate for bridge sensor excitation. TABLE: Current Sourcing
Limits
(p. 424)
lists the current limits of 12V and 5V terminals. Greatly reduced
output voltages on these terminals may occur if the current limits are exceeded.
See Terminals Configured for Control
(p. 428)
for more information.
Current Source and Sink Limits
Terminal
Limit
1
VX or EX (voltage excitation)
2
±50 mA maximum
IX (current excitation) ±2500 µA maximum
CAO (continuous analog voltage output) ±15 mA maximum
SW12V
3
< 900 mA @ 20°C
< 630 mA @ 50°C
< 450 mA @ 70°C
< 360 mA @ 85°C
12V + SW12V (combined)
4
< 1.85 A @ 20°C
< 1.33 A @ 50°C
< 1.00 A @ 70°C
< 0.74 A @ 85°C
5V + CS I/O (combined)
5
< 200 mA
1
Source is positive amperage (+); sink is negative amperage (–).
2
Exceeding current limits will cause voltage output to become unstable. Voltage should stabilize
once current is again reduced to within stated limits.
3
A polyfuse is used to limit power. Result of overload is a voltage drop. To reset, disconnect and
allow circuit to cool.