Casella CEL Tipping bucket rain gauge User Manual
Page 12
6.
COUNTING THE BUCKET TIPS
A variety of devices may be used to count the bucket tips, these include:
¤
Data Loggers (with contact closure input capability),
¤
Event counter (a simple LCD counter to indicate bucket tips),
¤
Chart Recorder,
¤
Computer data acquisition system.
Consideration should be given to ensure that the counting/logging device
used can accept a contact closure input.
For fast counter inputs, some form of capacitor-resistor filtering may be
necessary to reduce “bounce” effects in the contact signal.
For details of suitable logging devices please contact the Casella CEL sales
department.
6.1
Reed Switch Details
Switching contact closure time is typically less than 100 milli-seconds for 0.2
mm of rain (N.B. closure time will be faster for 0.5 mm of rain).
Maximum current rating
300 mA
Breakdown voltage
200 V D.C. minimum
Contact resistance
150 m
Ω
Insulation resistance
10
9
Ω
Capacitance open contacts
0.2 pF
Life
10
6
operations.
Reed switch connections are made via a 2 way terminal block (see Figure 5).
Counting
Figure 5: Connections for reed switch
Page 12 of 16
Tipping Bucket Rain Gauges
User Manual