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Relay and Optocoupler Applications

Benefit from more than 35 years of experience.

Discover vividly illustrated application examples and learn all about the domains of use and technologies.

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Application Examples

Interesting Information and Applications

Control Relay for Ex Applications

Control Relay for Ex Applications

Fast and flexible: Relays from WAGO are suitable for use in Zone 2 explosive atmospheres and thus cover a wide range of applications.

Hazardous Areas

Hazardous areas arise in various applications including the chemical industry, during the production of crude oil or natural gas and in the food industry. These are divided into Zones 0, 1 and 2 according to the frequency and duration of occurrence of potentially explosive atmospheres. WAGO relays are suitable for use in Zone 2 explosive atmospheres. For devices that may be used in hazardous areas, labeling is mandatory.

In order to reduce costs but still be able to install the products in the Ex area, facility operators try to use devices with Zone 2 approval.

A type examination certificate or manufacturer’s declaration is required for use in hazardous areas. You can download these from the eShop and add them to your system documentation.

Zone 2

Area in which it is not anticipated during normal operation that a potentially explosive atmosphere will occur as a mixture of flammable materials in the form of gas, vapor or mist with air. If one does occur, then only momentarily.

Control Relay for Systems with Long Cables

Control Relay for Systems with Long Cables

Reliable switching despite coupling: To switch on, relay modules require nominal voltage UN. For operation, however, a holding voltage that’s just 15 % of the nominal voltage is sufficient. In standard circuits, all relay modules operate reliably. However, in circuits with long parallel lines, or those with either active two-wire sensors or digital AC control outputs, a low holding voltage often leads to malfunction. The modules no longer switch off.

This effect often occurs when systems are updated, switching over from old “power-hungry” relays modules to “power-saving” ones.

What are the causes and how can they be eliminated?

Long parallel lines are capacitively coupled to each other. Energy is then transferred to an adjacent conductor. Active two-wire sensors, such as proximity sensors or level monitors, normally require a minimum continuous current to ensure that the holding voltage is maintained on the relay control lines. Because of this behavior, the relay cannot switch correctly.

For such applications, WAGO has developed specific RC base load modules to protect against interference coupling and integrated them into the relay modules. These modules minimize the unwanted voltages at low loss and allow defined switching.

Lighting Systems and Control Relays for Lighting Systems