ENGLISH
14
OPERATING FUNCTIONS
O N -O FF m ode
The unit has an ON-OFF mode which switches on (or off if the reverse mode is ON) the output relays to control Constant / ON-OFF
metering pumps, peristaltic pumps or other ON-OFF equipment.
D I R E C T / R E V E R S E di recti on
The setpoint relays are factory set as follows:
Setpoint 1 PH:
ACID mode, the output is active when the measured value is higher than the selected setpoint, the connected pump
meters out an acid product.
Setpoint 2 PH:
ALKALINE mode, the output is active when the measured value is lower than the selected setpoint, the connected
pump meters out an alkaline product.
Setpoint 1 RX:
DIRECT mode, the output is active when the measured value is lower than the selected setpoint, the connected
pump meters out an Oxidising product.
Setpoint 2 RX:
REVERSE, the output is active when the measured value is higher than the selected setpoint, the connected pump
meters out a reducing product.
Setpoint 3 CL:
DIRECT mode, the output is active when the measured value is lower than the selected setpoint. REVERSE mode,
the output is active when the measured value is higher than the selected setpoint.
A L A R M M I N / MA X functi on
The
Alarm
function makes it possible to select the minimum and maximum values outside which the instrument goes into alarm
mode.
H Y S T E R E S I S
Hysteresis
is useful during operations to adjust the setpoints in ON-OFF mode and is used to enable or disable the output relays
when the selected hysteresis has been achieved. Hysteresis is useful when there are too many quick swings around the setpoint, that might
damage the connected device. By increasing hysteresis it is possible to move away from the setpoint in accordance with the required value.
Example
PH
: if the selected set point is 7.00 pH and hysteresis is set at 0.05, the two active points are 6.95 pH and 7.05 pH: within this
range, the set point is OFF and the outputs are blocked, outside this range the set point is ON (always in accordance with Acid or alkaline mode).
The
RX
parameter (mV) works in the same way indicating values in mV. The chlorine measurement
CL
works according to the values for the
selected chlorine range showing values in ppm.
D E L A Y o u tput response del ay on set poi nt
The Delay time
blocks the output relays (max 999 sec. programmable) to ensure the outputs are active only when the sensor
measurements are stable, thus assuring the best results in terms of chemical balance.
P R O P O R T IO N A L PW M m ode: Ti m ed “Pul se W i dth M odul a ti on”
PWM
“pulse width modulation” support a proportional mode on each ON-OFF setpoint activating at the pulse, with a change of the
Start/Stop cycle time according to the measured value with respect to the setpoint.
Pulse width:
pulses are timed ON and OFF based on the distance from the selected setpoint, programmable, example: if the selected
setpoint is 7.00 pH and the measured value is 9.00 pH, if the selected value of the
PWM
mode is 1.50 pH, the proportional function starts
after reaching 8.50 pH with Time/Pause pulses and decreasing the active time while reaching the setpoint.
Cycle Time:
selected value of the
PWM
mode 1.50 pH with a 60 second cycle (programmable), example: setpoint is 7.00 pH, at
measured value 8.50 pH = active time 60 sec - pause time = 0 sec; 7.75 pH active time = 30 sec - pause time = 30 sec… decreasing the
active time as a consequence while reaching the setpoint. The cycle time depends on many variables, such as: distance from the injection
point of the system to be treated, how fast or slowly the setpoint needs to react, chemical concentration, etc.
MIN Active Time:
programmable. Defines the minimum time for which PWM is active; prevails over the selected settings. The pulse
modulation function is adjusted with 3 functions according to the following formula: Active Time in accordance with the selected formula =
(measured value - setpoint) / (period width * cycle time). If the result of the formula is
<
than that chosen with MIN Active Time, the latter
prevails on the former, example: measured value 8.50 pH; setpoint 7.00 pH / Period Width 1.50 * Cycle time 60 sec = active time 4 sec. If the
user has selected
Active time min
5 sec, this will be the minimum PWM time and not 4 sec.
The
RX
parameters (mV) work in the same way indicating values in mV.