What does a relay actually do
What does a relay actually do?
One of the most important components of Schabus products is the relay. Whether as a potential-free contact in the exhaust air controls, for shutting off the washing machine during aqua stop, or as an alarm notification from the gas detector, every switching process is handled by a relay.
A relay is simply a switch that isn't operated manually, but rather by electronics. The greatest advantage of a relay is that it can switch large amounts of power with very low currents from the electronics.
A relay that is accessible via screw terminals, e.g., in the FDS 100, SHT 5001, GX-A1+, etc., is always designed as a potential-free changeover relay at Elektrotechnik Schabus. "Potential-free" in this context means that there is no potential, i.e., no voltage, at the relay; nothing comes out of a relay because it is simply a switch. You decide what you want to switch with the switch. And "changeover relay" means that you always have two switching contacts: an opener (NC) and a makeer (NO), as well as a common contact (COM).
o a relay contact is shown, here from a SHT 5002 level controller:
10: common connection
(com) = common
11: Normally open contact
(no) = normally open
12: Normally closed contact
(nc) = normally closed
The diagram always shows the relay not actuated; it is said to be "not energized." The term comes from the relay's internal workings, where a coil magnetically "attracts" the switching blade.
On some Elektrotechnik Schabus devices, the relays are energized in monitoring mode when switched on, e.g., the SHT 5000. Other devices, such as the SHT 5001, only energize the relay when an event has actually occurred. Always refer to the article on relays in the operating instructions, which provides information about the relay switching states.
Relays are also used in our socket devices, which are connected and switched through. Usually, a single-phase connection or disconnection is performed, and a potential is present here, namely the AC mains voltage. Socket devices are not potential-free contacts!
A special case is the BBB300 (item no. 200603 ) . With this small component, you can turn a switched socket into a potential-free contact. The BBB300 contains a high-quality Finder® relay with gold-rhodium contacts, which can switch both extremely low currents and voltages as well as higher power levels. This relay only operates as a normally open contact, meaning that when the socket is switched on, the normally open contact is closed, thus providing a stable connection between the two contacts.
