A-96.250.451 / 190121
AMI Deltacon Power
Product Description
11
Alarm Relay
One potential free contact alternatively:
Open during normal operation, closed on error and loss of
power.
Closed during normal operation, open on error and loss of
power.
Summary alarm indication for programmable alarm values and in
-
strument faults.
Input
For potential-free contact to freeze the measuring value or to inter
-
rupt control in automated installations (
hold
function or
remote-off).
Communica
-
tion interface
(optional)
USB Interface for logger download
Third signal output (can be used in parallel to the USB interface)
RS485 with Fieldbus protocol Modbus or Profibus DP
HART interface
Safety
Features
No data loss after power failure. All data is saved in non-volatile
memory.
Over voltage protection of in- and outputs.
Galvanic separation of measuring inputs and signal outputs.
Measuring
principle
When a voltage is set between two electrodes in an electrolyte solu
-
tion, the result is an electric field which exerts force on the charged
ions: the positively charged cations move towards the negative elec
-
trode (cathode) and the negatively charged anions towards the posi
-
tive electrode (anode). The ions, by way of capture or release of
electrons at the electrodes, are discharged and so a current
I
flows
through this cycle and the Ohms law
V = I×R
applies. From the total
resistance
R
of the current loop, only the resistance of the electrolyte
solution, respectively its conductivity
1
/
R
, is of interest.
The cell constant of the sensor is determined by the manufacturer
and is printed on the sensor label. If the cell constant has been pro
-
grammed in the transmitter, the instrument measures correctly. No
calibration needs to be done, the sensor is factory calibrated. Mea
-
suring unit is
S/cm or
S/m.
Specific
Conductivity
Conductivity from all ions in the sample, mainly the alkalization
agent. The contribution of impurities is masked by the alkalization
agent.
Cation Con
-
ductivity (Acid
Conductivity)
The alkalization agent is removed in the cation column. All cationic
ions are exchanged with H+, all anionic impurities (ions with negative
charge) pass through the column unchanged.
