Urahara
Member
Hi
I intend to use a MCU pin to control, via a npn transistor, a 9V DC relay coil which switches on the primary of a transformer (inductive load?) of a device. Let's say the load takes up either max 4A/240VAC, or 5A/110VAC).
On the DC end, I know it is recommended to use a flyback diode to handle the voltage spike to protect the transistor from damage.
My questions are on the AC end :
1) To protect the relay contacts, it is recommended to use a RC snubber network across the contacts. If I use a relay that can handle 10A resistive load, such as **broken link removed** is the snubber circuit necessary?
2) Actually my true concern abt the snubber circuit is about 'safety' since I think there is AC current flowing even when the relay is off. Is this a real concern? If a RC circuit of 100ohms-0.1uF is used, how do we calculate the current flowing?
Thks!
I intend to use a MCU pin to control, via a npn transistor, a 9V DC relay coil which switches on the primary of a transformer (inductive load?) of a device. Let's say the load takes up either max 4A/240VAC, or 5A/110VAC).
On the DC end, I know it is recommended to use a flyback diode to handle the voltage spike to protect the transistor from damage.
My questions are on the AC end :
1) To protect the relay contacts, it is recommended to use a RC snubber network across the contacts. If I use a relay that can handle 10A resistive load, such as **broken link removed** is the snubber circuit necessary?
2) Actually my true concern abt the snubber circuit is about 'safety' since I think there is AC current flowing even when the relay is off. Is this a real concern? If a RC circuit of 100ohms-0.1uF is used, how do we calculate the current flowing?
Thks!