How does a dual coil latching relay work?

Magnetic Latching relays can have either single or dual coils. On a single coil device, the relay will operate in one direction when power is applied with one polarity, and will reset when the polarity is reversed. On a dual coil device, when polarized voltage is applied to the reset coil the contacts will transition.

How do you reset a latching relay?

Resetting is very simple. The coil circuit needs to be opened and shortened to the coils ground potential. The capacitor will be discharged through the coil and drives a current pulse with opposite polarity through the coil, that resets the relay (Figure 4).

Is there a latching relay?

A latching relay is a two-position electrically actuated switch that maintains either contact position indefinitely without any power being sent to the coil and is a perfect choice to reduce the power consumption of a system. It is not necessary for power to remain applied to maintain the switched state.

What is the difference between a latching and non-latching relay?

Both types of relays in similar in design and function, however, a significant difference between them is that a latching relay will remain in the last position it when it was last powered, whereas a non-latching goes back to its normal position. This makes each more type of relay suitable for different applications.

Where is latching relay used?

Relays are typically used when small continuous electrical currents must be used. A latching relay, however, is used to control large currents with smaller ones, using a pulse to move the switch that then stays in position, and this reduces the power requirement slightly.

What does A1 and A2 mean on a contactor?

One side of the contactor coil (A2) is connected directly to one of the incoming power lines. The other side of the coil (A1) has two possible pathways to complete a connection to the other incoming power line.

How does a latch relay work?

A latching relay is a two-position electrically-actuated switch. It maintains either contact position indefinitely without power applied to the coil. It is controlled by two momentary-acting switches or sensors, one that ‘sets’ the relay, and the other ‘resets’ the relay.

What is the difference between a latching and non latching relay?

The diagram below shows a dual-coil latching relay. Each of its coils is connected to a normally open (NO) pushbutton switch. When switch SW 1 is pressed for a moment the relay contacts latch in one direction and the track polarity has “+” on one rail and “-” on the other.

How does the latch work on a bistable relay?

A bistable, or mechanically latched relay typically has two internal coils and an internal latch mechanism. Energizing one coil ‘sets’ the contacts in one position, and the contacts stay in that position until the ‘reset’ coil is energized.

What kind of transistor does a dual coil relay need?

The dual coil relay will need two NPN transistor switches similar to your J1. One for SET and one for RESET. The single coil probably requires coil voltage reversal for SET and RESET. This requires a H-bridge arrangement and, while the relay is simpler, the switching electronics is more complex.

Can a single coil relay be used for a reverse loop?

A simpler solution is to wire a common DPDT single coil relay to one set of the dual coil relay’s contacts so that the smaller relay does nothing more than activate the larger relay. The schematic below shows one way to accomplish this. Reverse Loop Controller