I have wired pin 30 directly to a 12 volt battery (thru a breaker). The output from pin 87 is connected to a motor speed controller (PWM). After turning on the circuit, the PWM buzzed for a split second and then blew it's internal fuse link. The PWM is rated for 100 amps max, 60 amps continuous and the entire circuit is protected by a 40 amp breaker, which did not trip.
2 Answers
I can’t see anything on the Novita website that says that the RL44 is a solid state relay, it just looks like a normal electro-mechanical relay to me.
With pin 30 connected to 12v, pin 87 should be able to deliver 40A max to the load, so you have wired it correctly.
Incorrectly wiring the relay would not cause the internal fuse of the motor speed controller to blow unless you have got the battery polarity incorrect.
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1Thanks for the comments! I think the problem was a short at the motor connection terminals, as there just barely room on the PWM terminal block for the 10 gage connectors - its in a tight space and hard to see.– RogerCommented May 13 at 15:00
Disconnect the pwm from pin 87 and power up the relay. Pin 87 should not have 12v with relay OFF, 12v with relay ON. This verifies 87A relay wiring is correct. However, the pwm may not operate on the straight 12v power, shorting the internal fuse. If I'm not mistaken, pulse width modulation means the input signal is a high frequency square wave signal, while the width of the pulse varies - a variable high speed switching circuit to vary current output to whatever device it controls; analog meter, stepper motor/servo, etc. This may be an incorrect circuit to control the pwm device.
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Thanks for the suggestion and the drawing! The PWM terminal block is very narrow and mounted in an area where it is hard to see. I believe that the 10 gage wire connectors on the PWM output may have been shorted. I– RogerCommented May 13 at 15:08