ATI
MetriNet
Water Quality System
Part 3
– Installation
20
O&M Manual
Rev-C (05/20)
C-Solenoid Power
- At 12VDC, the flow solenoids is pulse driven for only an instant, 2A @ 200
ms) to change state. The solenoid is used to limit water loss.
D-Modem Power
– At 12VDC, the modem consumes 100 mA max for about 2 minutes max at
each call.
Assume user sets the following cycle settings on a system with 1 sensor
–
-Modem uploads twice per day (not shown in Fig 14 below)
-Poll rate 15 minutes. Sensor power-up and measurement rate.
-PU delay 30 seconds, On-time of sensors once powered up.
-Solenoid delay 30 seconds, Wait time after solenoid changes state
FIXED SOLENOID
TIME OF
200ms
2A @
12VDC
SOLENOID
POWER
SOLENOID
DELAY
30s
PU
DELAY
30s
MEASURE
SENSORS
2s
3.2 mA
@12VDC
AVG TOTAL
POWER
6.5mA
@12VDC
RUN POWER
2.8mA
@ 2VDC
SLEEP POWER
POLE RATE
15 MINUTE
CYCLE
CYCLES
CONTINUE
ALL DAY
Figure 14
– Average vs Pulse Power, and State Diagram
Using pulse-
power calculations to get average power…
https://www.vishay.com/resistors/pulse-energy-calculator/
Average power of “pulsed” modem calling in twice per day for 2 minutes – 3.33 mW per day
Average power of 30 second
“pulsed” run mode w/1 sensor – 1.2 mW per day
Average power of 14 minutes of Sleep mode (2.8 mA x 12 VDC)
– 33.6 mW per day
Total average power = 3.33 + 1.2 + 33.6 =
38.1 mW, or 3.2 mADC average @ 12VDC
3.87
Battery Pack Sizing
For the cycled battery mode MetriNet, the calculations of section 3.86 can be used to estimate
the size of the battery required for the desired run time.