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operate independently of the On or Off Delay Time setting(s) and will energize and de-energize without delay
when needed.
5.3.19
Relay, Target PPM Control Mode
ONLY AVAILABLE IF HVAC MODE IS ENABLED
Overview
In Target PPM control mode, the controller monitors the total volume of flow through up to two analog or digital
flow meters, and after a programmable volume has been accumulated, the relay activates for a calculated time to
achieve a target PPM level.
The user enters the target PPM, the volume of water to trigger the chemical feed, and the data necessary to calcu-
late the pump on-time required to maintain the target PPM in that volume of water.
Pump On-Time (sec.) = Accumulated Volume (gal or l) x Target PPM x 0.0036
Cycles x Pump Capacity (gal or l/hr.) x Pump Setting (%) x Specific Gravity (g/cm3)
Pump On-Time (sec.) = Accumulated Volume (m3) x Target PPM x 3.6
Cycles x Pump Capacity (I/hr) x Pump Setting (%) x Specific Gravity (g/cm3)
Control Operation
As flow accumulates, the controller updates a field called Accumulator Total. When this value is greater than or
equal to the value set for the Accumulator Volume, the relay activates for the calculated number of seconds, and the
accumulated total is reduced by the accumulator volume amount.
If the trigger volume is achieved again before the activation time has expired, the newly calculated on-time per
unit volume is added to the remaining on-time. If the relay state is continuously on for longer than the Output Time
Limit, then relay will deactivate.
Output Details
The details for this type of output include the relay on/off state, HOA mode or Interlock status, total accumulated
on-time, alarms related to this output, current cycle on time, remaining on-time, accumulator total, disturbance
input value (if used) and adjusted target setpoint (if disturbance input is used), cycles of concentration, relay type
and the current control mode setting.
Settings
Touch the Settings icon to view or change the settings related to the relay
Target
Enter the desired PPM set point for the product.
Pump Capacity
Enter the maximum flow rate for the metering pump.
Pump Setting
Enter the stroke length setting for the metering pump, in percent.
Specific Gravity
Enter the specific gravity of the product to be added.
Accumulator Volume
Enter the volume of water passing through the water meter to trigger the chemical feed.
Flow Input
Select the flow meter to be used as an input for this control relay.
Flow Input 2
Select the second flow meter, if any, to be used as an input for this control relay.
Cycles Input
Select the virtual input that is programmed as a Ratio calculation of the system
conductivity/makeup conductivity, or select None.
Low Cycles Limit
Enter the lower limit for cycles of concentration, if used. The calculated on-time is
limited to a maximum value if the cycles of concentration gets too low.
Disturbance Input
Select the virtual input or control output that will multiplied by the control setpoint
(Target ppm setpoint). A typical application for this is to use a corrosion sensor as the
disturbance input to adjust the PPM setpoint.