PPS
PPS K02/0416
page 7
Contact types
Model PPS-1201, Normally closed
The contact is opened when the flow increases and the set point value is
reached or exceeded. The switch closes again with falling flow at the minimum
value influenced by the switch hysteresis.
Model PPS-1202, Normally open
The contact is closed when the flow increases and the set point value is
reached or exceeded. The switch opens again with falling flow at the minimum
value influenced by the switch hysteresis.
Model PPS-1203 and model PPS-3203, changeover contact
The contact 1-2 is closed and the contact 1-3 is opened when the flow
increases and the set point value is reached or exceeded. The switch
backspaces again with falling flow at the minimum value influenced by the
switch hysteresis
Hysteresis
Defined as the difference between the opening and closing flow values of a
contact.
For example, the model PPS-1202 in tube with 11/4" ID, set at about 36 L/min
increasing set point will reset at about 18 L/min decreasing. Contact hysteresis =
18 L/min.
Contact protection
The reed contact may be damaged if the switch ratings are exceeded, especially
while switching inductive or capacitive loads. This can cause dangerous
situations. By the use of a contact protection relay, this problem can be overcome
and the lifespan and switch rating of the reed contact can be greatly increased.
(e. g. model MSR 10).
