LTH Electronics MTD75, Operation Manual

Page: 64 / 266

Biocide A
- 62 - MTD75 Operation Guide
Biocide
A
Output Configuration
Depending on the trigger selected the relay output can be configured to operate as an “On/Off”
output, a “Pulse” output or a “Time Proportional” output.
When the output is set to “Pulse” the user can select the “Stroke Rate” which is the frequency of the
output pulses. The output pulse width is fixed at 0.2 seconds.
When the output is set to “Time Proportional” the user can select the “Cycle Time” which is the sum of
the on and the off times. The user can also select the “Proportional Band” over which the proportional
timing is active. For example for a redox setpoint of 1000mV and a band of 100mV was entered. When
the reading falls below 900mV the relay would be energised, as the input rises and approaches the set
point the biocide relay starts to cycle on and off with the on time reducing and the off time increasing,
respectively.
Bleed Inhibiting
The facility has been provided to allow the user to inhibit any Bleed operations during and for a period
after, the Biocide A dose. The period of the Bleed Inhibit can be set from 00:00 to 24:00 hours. When
the Bleed Inhibit is set to 00:00, the Bleed operation will be inhibited only for the duration of the
Biocide A dose. Only available if the Bleed relay has been enabled.
Pre-Dose Bleeding
The MTD75 provides the user with the option to define a short Bleed operation before initiating the
Biocide A Dose, this can be defined from 1 second to 99 minutes. NB. If a bleed inhibit occurs during a
pre-bleed operation the pre-bleed will be terminated and the Biocide dose initiated immediately. Only
available if the Bleed relay has been enabled.
Dose Alarm Timer
To prevent the occurrence of overdosing when using the “Redox” trigger, the user can define an
“Alarm Time”. If the dose relay remains active for longer than this set period the system will deactivate
the relay, flash the Biocide A LED on the front panel and display the “Dose Alarm” message in the
Biocide A section of the main display. To cancel the alarm and re-enable the dose relay the user needs
to press the “ACK” button on the front screen and select Biocide A from the list.
Manual Dosing
To provide some flexibility in setting up and adjusting the dosing, the MTD75 is provided with a
“Manual Dosing” option. Selecting the “Manual Dose: Start” option will activate the relay for the time
set in the manual dose duration menu. If the user requires the manual dose to terminate before the
timer runs out select the “Manual Dose: Stop” menu.