1.0 INTRODUCTION
The Walchem WDT400 Series controllers offer conductivity control of cooling tower water and control
of corrosion/scale inhibitor feed. The inhibitor pump may be selected to operate in one of the following
modes:
Feed and Bleed
Feed and Bleed with Lockout
Feed as a percent of Bleed
Feed as a percent of Time
Feed based on a Water Contactor input
Feed based on a Paddlewheel input
The WDT series cooling tower controllers are supplied with temperature compensated electrodes with a
cell constant of 1.0. The controllers are microprocessor driven industrial type with on/off control
outputs. A timed sample mode may be selected, and on small towers can reduce installation costs by
eliminating the need for a sampling bypass line. One or two optional isolated 4-20 mA outputs that are
proportional to the conductivity reading are available for all models.
Any set point may be viewed without interrupting control. Each set point change will take effect as soon
as it is entered. An access code is available to protect set point parameters, while still allowing settings
to be viewed.
All outputs are interlocked with a flow switch input.
An alarm relay is provided with WDT400 models. It is triggered by:
Temp A or B Error
Cond A or B Error
No Flow Tower A or B
Bleed A or B Timeout
Feed A or B Timeout
Tower A or B Hi Alarm
Tower A or B Lo Alarm
Our unique USB feature provides the ability to upgrade the software in the controller to the latest
version.
An advanced USB capability option is available. The Config file feature allows you to save all the set
points from a controller onto a USB flash disk, and then import them into another controller, making the
programming of multiple controllers fast and easy. The data logging feature allows you to save the last
2 month’s readings and events to a USB flash disk.
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