JohdotaAn impulse relay changes the state of its contacts every time its coil gets a voltage pulse. The first press switches the light on and the next one switches it off. The relay remembers its state mechanically, so no self-holding is needed.
Wiring
- The control push-buttons are NO, and they are wired in parallel in the supply to the coil A1–A2.
- Any of the buttons gives a pulse, so the light can be controlled from any of the places. More buttons can be added in parallel as needed. Illuminated push-buttons are an exception: one manufacturer requires an extra module across the coil and allows at most 15 of them.
- A contact of the relay switches the lighting.
Remember
- The coil is controlled with short pulses. For example, one manufacturer's impulse relays allow a pulse length from 0.1 s to one hour, so the coil must not be left energised all the time.
- Many impulse relays have a manual lever for changing the state by hand.
- Impulse relays also come in multi-step versions, where successive pulses switch the contacts in turn in different sequences.
Frequently asked questions
How do you control a light from several places with an impulse relay?
Wire NO push-buttons in parallel to the coil A1–A2. Each press switches the light over, and you can add as many buttons as needed. Illuminated buttons may need a module across the coil.
How does an impulse relay work?
Each voltage pulse to the coil changes the state of the contacts: the first press switches the light on, the next one off. It remembers its state mechanically.
Does an impulse relay need a self-holding circuit?
No. It remembers its state mechanically, so the light stays on without self-holding.
Can the coil of an impulse relay be left energised?
No. The coil is driven with short pulses. One manufacturer, for example, allows 0.1 s to one hour.