Can my relay handle his kind of abuse? or will it die?

Thread Starter

A Homeschoolers Workbench

Joined Jul 26, 2016
142

MaxHeadRoom

Joined Jul 18, 2013
22,707
If switching with an Arduino why not use a Triac, with zero cross switching opto to drive it?
Look up Fairchild app note AN-3006, or you could use an off the shelf SSR.
Max.
 

MaxHeadRoom

Joined Jul 18, 2013
22,707
Here is the basic circuit, very simple using a MOC316x series opto (IC1).
upload_2016-12-21_12-1-3.png
The MOC3022 series are random trigger, you need zero crossing type, also that triac is a little light at 8amps.
AN-3006
Max.
 
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Thread Starter

A Homeschoolers Workbench

Joined Jul 26, 2016
142
I doubt that you can build an Arduino circuit to detect AC current cheaper than that ebay device.
You are incorrect in that assumption, I can get an arduino pro mini for 2$ but that Current Sensor Module is 12$, I think I am going to try to use a Triac, again does anyone have a good source on Triacs so I can learn about them.
AIDayley
 

PlasmaT

Joined Feb 19, 2015
61
Use a resistor parallel to the relay coil. This will reduce current across the relay coil.
Based on the current the motor needs to operate, you may have to choose a resistor of low resistance.
for e.g. If the motor needs 15A, then consider a 0.4 Ohm resistor (a shunt resistor) to give about 5V for the relay to operate.
 

AlbertHall

Joined Jun 4, 2014
11,156
Use a resistor parallel to the relay coil. This will reduce current across the relay coil.
Based on the current the motor needs to operate, you may have to choose a resistor of low resistance.
for e.g. If the motor needs 15A, then consider a 0.4 Ohm resistor (a shunt resistor) to give about 5V for the relay to operate.
Then you will need a 5V AC relay.
 

PlasmaT

Joined Feb 19, 2015
61
Yes. But note that the resistor will have to have the required wattage and heat sinking is required. Well 90W :)
Or as AlbertHall has already suggested, use a current sensor and then drive the relay.
Alternatively use a hall effect sensor to detect the magnetic field around the 15A wire and then link it to the relay.
 
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