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What is flyback protection?
A “Flyback Voltage Spike” occurs when the supply current to an inductive load such as a solenoid is interrupted. Flyback voltage protection limits the voltage rise when the relay contacts open by safely draining away the energy stored in the solenoid coil.
Does a relay need a flyback diode?
Many applications of relays require a flyback diode to protect against inductive voltage.
How do you protect a relay?
To prevent damage you must connect a protection diode across the relay coil. Most relays are designed for PCB mounting but you can solder wires directly to the pins providing you take care to avoid melting the plastic case of the relay.
Why do you put a diode across a relay coil?
Placing a diode across a relay coil passes the back electro magnetic field and its current through the diode when the relay is energized as the back EMF drives the flyback protection diode in forward bias. Tiny flyback diodes prevent huge flyback voltage from damaging your components.
What is the purpose of a flyback diode?
To prevent the reverse polarity voltage pulse on switch turnoff, a flyback diode is connected in parallel across the inductor. The function of the flyback diode is to allow an electric current to pass in one direction only, while blocking it in the opposite direction.
Can you put a relay in backwards?
Relays can’t be inserted backwards. The ones you can put in two ways, will work either way.
Where to place a flyback protection diode in a relay?
Tiny flyback diodes prevent huge flyback voltage from damaging your components. The placement of a flyback protection diode is rather simple; it should be placed directly across the relay’s coil. A schematic for a freewheeling diode circuit in a relay is shown below.
Why do I need A flyback voltage protection?
Any switching circuit for highly inductive loads should have flyback voltage protection to limit the voltage rise from the discharging coil and damage to the relay contacts. Flyback voltage protection limits the voltage rise when the relay contacts open by safely draining away the energy stored in the solenoid coil.
What should the reverse voltage of a relay be?
In your relay, the coil current is shown as 79.4 mA. Specify a diode for at least 79.4 mA current. In your case, a 1N4001 current rating far exceeds the requirement. The diode reverse voltage rating should be at least the voltage applied to the relay coil. Normally a designer puts in plenty of reserve in the reverse rating.
Why are snubber diodes called Flyback diodes?
You may have heard the term flyback diode — also known as, “snubber diode,” “suppressor diode,” and many other names. Regardless of their name, flyback diodes can be an important tool to prolong the life of your inductive circuits. Inductor voltage spikes: switch arcing