Impulse relays

Pulse relays

Pulse relays, also known as bistable, holding or latching relays, belong to the group of electromagnetic relays widely used in the power industry. Of course, apart from this type of device, there are also other types of relays on the market, such as electronic static relays or digital devices (e.g. transmission gates).

How does a pulse relay work?

A pulse relay is used for the same purposes as other relays, ie to change the state of the output circuit or circuits under certain input conditions.

In an electromagnetic pulse relay, the first pulse applied to the coil switches the device on, and the second one disconnects it. In the event of a power failure, the device retains the last setting and does not return to the original setting - this is what the bistability of the relay is all about. The apparatus is stable in both short-circuited and open working (secondary) circuits. Thanks to this property, the relay consumes energy only temporarily, at the time needed for switching, which significantly reduces the current consumption. It is not necessary to maintain the potential difference at the ends of the control circuit while the relay is on. It is worth knowing that there are also impulse relays on the market that use a permanent magnet instead of an electromagnet in their design - however, they are less common than devices based on an electromagnet, although they fulfill the same function.

Timed, group and sequence relays

The impulse relays are divided into 4 groups due to the differences in the implementation of circuit control. Although the differences in the design of the devices are not significant, they allow the use of various control mechanisms of the input circuit (control). So we distinguish between relays:

1. on-off : impulse on-off relays are designed to control a single circuit to which usually only one electric receiver is connected. The control system then consists of a relay which controls the operation of the secondary circuit. The design is simple, and at the same time allows you to manage electricity consumption.
2. with timer : relays equipped with time switches allow not only to switch the circuit on or off with a button, but also to switch off (or switch on) the receivers by default after a specified, set time. Built-in timer relay, it will open or close the controlled secondary circuit automatically. It allows for some automation of the process of switching off or switching on of receivers controlled by a relay.
3. group : these are complex multi-relay circuits that allow the control of working circuits in several ways - for example, as is the case with on-off devices, but in a specific area. Let us consider the example of staircase lighting in a multi-family building. The relay located on the 3rd floor will allow the lighting of the 3rd floor corridor to be turned on, while all other corridors will remain unlit. Similarly, the relay from the lower floor will activate the lighting of the corridor on the second floor. At the same time, the master set of relays will turn on / off the switch (turning off the lighting in corridors 2 and 3) or will centrally close all circuits controlled by local relays.
4. sequential : these kinds of relays control two or more circuits with the push of a button. However, unlike group relays, sequence devices do not have central control and all operations are performed from a local relay.

How to choose the right impulse relay?

Regardless of the purpose of the bistable relay, when choosing a device appropriate to our needs, we should take into account the following parameters:

1. contact currents,
2. mounting method (rail or box),
3. control method,
4. manufacturer and price.

Pulse relays are relatively expensive devices, therefore the option to buy a relay of an unknown brand seems tempting. However, it is not worth being deluded - only high-quality products from proven producers guarantee durability and impeccable operation of the cameras.