In power installations, relays are used for galvanic separation of different voltage potentials. In addition to this isolation, relays with forcibly guided contacts must guarantee mechanical interlocking of the contacts. In corresponding applications at least one contact is used for control, and further contacts serve for either control or load switching purposes. In normal power relays, galvanic separation is usually only effected between coil and contact block, in the case of relays with forcibly guided contacts, isolation of different voltage potentials must also be guaranteed within the contact block.

Galvanic separation within the contact block

Relays with forcibly guided contacts are used in applications relying upon a high degree of safety. Thanks to the forcibly guided contacts and high voltage isolation characteristics, they guarantee the protection of people and equipment over the full life span of the relay including fault conditions.
The separation of the power circuits is achieved with suitably dimensioned insulation between live components (basic insulation, extra insulation, reinforced insulation, EEx insulation). The creepage distances and clearances are defined in accordance with the insulation voltage. The control side of the relay to the output contacts and also the output contacts among themselves are spaced with the required isolation distances. With the products of ELESTA relays GmbH, an isolation voltage of >250V specified for many applications can even be guaranteed for the case of "safe separation".