|
Another critical part of the new WPS platform is a new conductivity meter.
Where the turbidity sensor monitors dirt and food particles in the wash water,
the conductivity sensor measures the electrical conductivity. By measuring
wash water conductivity, it is possible to determine the presence of detergent
in the wash solution.
The conductivity sensor samples the electrical conductivity
of water, a variable that changes with the chemical state of the
water. Water containing detergent, for example, is laden with ions,
making it more conductive. The conductivity sensor works when a voltage
is impressed on a pair of stainless steel electrodes exposed to the water.
The small amount of current that consequently
flows through the water is a measure of the water’s conductivity.
This sensor also began as a conceptual prototype at HTC. The challenges
in the development of the production sensor lay in identifying durable materials
for the electrodes, materials that could provide good electrical contact and avoid
galvanic corrosion. Circuit design was also important to ensure that the voltages
and currents would allow the electrodes to survive for many years in the harsh
environment of the dishwasher.
| 
.....
