Description

Application

Limit switches make or break circuits depending on the pointer setting of mechanical display measuring devices, such as pressure or differential pressure manometers or thermometers. Switch amplifiers are required to adapt the limit switches to the various tasks.

Design and mode of operation

The limit switch is installed below the dial (see fig.). It is designed so that the actual value display can move freely across the entire scale.

There is an adjustment lock attached to the front pane. Using a detachable adjustment key, the contacts mounted to the target value displays can be set to every point of the scale range.

If the contact arm that is connected to the actual value display reaches the contact pin on the target display, the power circuit is closed. An elastic connection between the contact arm and the actual value display keeps the contact closed until the actual value deviates from the set target value.

The actual value display can continue to move under a slight load exerted by the spring coupling. The installation space required to install the limit switches is formed by a high bayonet ring that forms a liquid-tight unit together with the basic casing (protection class IP65). The electrical connection is usually realised with a cable connection socket mounted to the side.