Setpoint
Once the input signal reaches setpoint the output relay switches off. A
dead band of 0.15pH (15mV) is used in normal mode. The relay output
switches on again at 0.15pH (15mV) above/below setpoint. (depending
on UP/dn mode)
Dosing mode
In normal dosing mode
[no.d]
the output relay simply switches on and
off below or above the setpoint. (depending on UP/dn mode)
In normal Proportional mode
[no.P]
the relay output starts to pulse on
and off once the input mV moves toward the setpoint. The difference of
input signal versus setpoint is controlled by the amount of “gradient” set
in the configuration program.
The lowest setting of 10 starts the output relay pulsing if 3.00pH (240
mV) below/above setpoint. The on/off ratio gradually reduces until the
relay switches off at setpoint.
Setting the gradient to the maximum of 100 starts the output relay
pulsing when 0.5pH (10 mV) below/above setpoint giving a very steep
gradient. The on/off ratio reduces very rapidly. (See Fig.6) for ‘gradient’
versus pulse output.
FIG. 6
Normal Proportional Dosing.
PAGE 22
PMH-2 Instruction manual
