Design And Function; Scope Of Delivery - WIKA 821 Mode D'emploi

2. Design and function

2. Design and function
2.1 Description
The switch contacts permanently installed in the pressure gauge close or open
at set limit values, depending on the switching function. Switching functions are:
Normally closed, normally open, change-over contact.
Instruments with switch contact model 821
Model 821 magnetic snap-action contacts are auxiliary current switches which
open or close connected electric circuits via a contact arm which is moved by the
instrument pointer.
Instruments with switch contact model 851
Model 851 reed contacts are auxiliary current switches which open or close con-
nected electric circuits at the set limit values via a permanent magnet which is
moved by the instrument pointer. The reed contacts used are bistable switches,
which keep their condition after a signal change up to the next actuation.
Instruments with switch contact model 830 E
The inductive contact with integrated model 830 E switching amplifier can switch
small loads directly. This is, for example, the case with applications with program-
mable logic controllers (PLCs).
The advantages of inductive contacts are the particularly fail-safe contact opera-
tion, no wear due to proximity contact operation as well as virtually no effect on the
measuring system.
No additional control unit is required.
The electronic contact is a 2- or 3-wire design with PNP output.

2.2 Scope of delivery

Cross-check scope of delivery with delivery note.
Operating instructions pressure gauges with switch contact models 821, 851 or 830 E
EN
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