Output Isolation (Galvanic Separation) - Honeywell Elster EK280 Applications Manual

EK280

8.1.4 Output isolation (galvanic separation)

Each of the four pulse and message outputs (terminals "DA1" to "DA4") can be isolated from the rest of the
EK280 circuitry. Isolation of the outputs decreases the CPU battery life. It is therefore advisable, prior to
isolation activation as described in these chapters, to estimate battery life.
Each pulse output via an isolated output requires additional power. The battery life therefore depends on the
following factors:
Number of isolated outputs
Number of pulses output
Duration of pulses output
To assess the influence of these factors, in the following some examples of battery life with various
combinations of these factors are given.
Since consumption and therefore base and measurement condition volume pulse outputs will vary widely
over the course of a year, it is useful to calculate the annual pulse output consumption.
The number of output pulses is moreover inversely proportional to the cp value of the output. To preserve
battery life, the chosen cp value of an isolated output should be as low as possible.
Also the adjustable pulse duration of an isolated output should be as low as possible, i.e. only as long as
required by the connected device.
The battery capacity required by an isolated output for pulse output is determined by the EK280 and
subtracted from the "BatRC" remaining battery life. However as the EK280 does not know how many pulses
are to be output in the future, the predicted remaining battery life "Bat.R" is derived from the remaining
battery life and calculated based on a default value.
Conditions:
Batteries: ......................... 1 battery pack
Mode input 1: .................. NF pulse input (mode1)
Sensors: .......................... 1 pressure and 1 temperature sensor
Communication: .............. Data transfer via modem with "Ring" signal, i.e. internal GSM modem or an analog
Readout duration: ........... 60 minutes per month
Display active: ................. Max. 60 minutes per month
Measurement cycle: ..... 30 seconds
Outputs: .......................... 1 isolated output (galvanic separation) / cp value= 1 Imp./m3
Battery life: ...................... 5.0 years approx. (5,000,000 m3 / pulse duration = 125 ms)
........................................ 5.0 years approx. (2,000,000 m3 / pulse duration = 250 ms)
........................................ 5.0 years approx. (1,000,000 m3 / pulse duration = 500 ms)
Outputs: .......................... 2 isolated outputs (galvanic separation) / cp value= 1 Imp./m3
Battery life: ...................... 5.0 years approx. (2,000,000 m3 / pulse duration = 125 ms)
........................................ 5.0 years approx. (1,000,000 m3 / pulse duration = 250 ms)
........................................ 5.0 years approx. (500,000 m3 / pulse duration = 500 ms)
Outputs: .......................... 1 isolated output (galvanic separation) / cp value= 10 Imp./m3
Battery life: ...................... 5.0 years approx. (500.000 m3 / pulse duration = 125 ms)
........................................ 5.0 years approx. (200.000 m3 / pulse duration = 250 ms)
........................................ 5.0 years approx. (100.000 m3 / pulse duration = 500 ms)
Outputs: .......................... 2 isolated outputs (galvanic separation) / cp value= 10 Imp./m3
Battery life: ...................... 5.0 years approx. (200,000 m3 / pulse duration = 125 ms)
........................................ 5.0 years approx. (100,000 m3 / pulse duration = 250 ms)
........................................ 5.0 years approx. (<100,000 m3 / pulse duration = 500 ms)
Application Manual
modem connected to terminals
74