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Electromechanical Switch Options
Switch Functions & Definitions
Wiring Instructions



Pressure Gauge With Electromechanical Contacts - 100mm & 160mm

Pressure gauges can be supplied with three types of electric alarm contacts: Electromechanical (Sliding design or Magnetic Snap Action design) which this data sheet relates to , Electronic (Non-Contact)  and  Inductive (Non-Contact).

General Information - Electrical Mechanical

Electromechanical switch contacts can be supplied in a simple sliding design where the two parts of the swich make contact at a set point or in a Magnetic "Snap Action" design where the two parts incorporate a magnet to firmly hold them together once they near each other. More details on the Magnetic design are given below. An electromechanical contact is essentially an auxiliary electrical switch which open or close electrical circuits at set points by means of a contact arm which is moved in accordance with the indicated value of the instrument pointer. The electromechanical contact consists of 3 main components

ØAn adjustable red setting pointer

ØThe carrier arm which is connected to the above red setting pointer and carries the primary contact pin

ØThe contact arm which is moved by the gauge pointer and which carries the secondary contact pin

A contact adjustment lock allows the user to adjust the setting pointer to the value at which the unit has to switch.

The gauge indicating pointer can freely move beyond the selected set point of the electrical contact which remains active allowing accurate measurement still to be made to the full scale of the instrument.

Magnetic "Snap Action" Spring Contact – Principle of Operation

Magnetic Spring Contacts have a permanent magnet screwed to the red setting pointer at the contact carrier arm. To close the circuit the contact pin is attracted by the magnet as it is carried to the contact point by the instrument indicating pointer and the contact closes. The snap action effect of the magnet reduces arcing between the contacts allowing for a greater switch rating.

Due to the increased contact force, the magnetic contact is also less sensitive to vibration. 

Switch Performance 

Nominal Supply Voltage – 250V Max

Making & Breaking Current – 1.0 A Max

Permanent Current 0.6 A Max

Switch Rating – 30W 50VA Max

Switching Accuracy – Approximately 2-5% of Full Scale Value

Operating Temperature - -20/+70C

Adjustment Range – 5-95% of Measuring Range

Volt Free Contact - Yes