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Dimming effect with the RC-4 Solid State when using 120V LED lights

Started by bsnut, November 06, 2014, 02:53:39 AM

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bsnut

I have been working on a project for the RC-4 for a Trolley Museum that belong to and noticed that the Solid State relays (SSR) don't turn off completely. So, I did some reading and learned that I don't have a enough load connected to the SSR, which causes the relay not to turn off and would like to let everyone how I'm going to solve this problem.

To solve this issue is, to connect a 2400 ohm 7 watt resistor in parallel for all relays using this low ampere LED lighting. This should solve my problem with the dimming effect.

Below, is the quote from page 22 from the datasheet that give me the answer to solve this issue.
Quote
Q : I have an SSR driving a load. The load turns on
okay, but never seems to turn off, unless I remove
power from the relay entirely. What might be happening?
A: This is normally a problem when using an SSR with a highimpedance
load, such as a neon lamp or a small solenoid.
Loads like these often have relatively large initial currents, but
relatively small "hold in" currents. The result is that the off-state
leakage current through the relay (see previous section) is
insufficient to cause the load to turn on to start with, but
sufficient to keep it on, once started. The solution is to place a
power resistor, sized for 8–10 times the rated maximum
leakage current for the SSR in parallel with the load. Make sure
that this resistor has a high enough power rating for the
application. For example, for a 5 mA leakage current at 120
VAC, a resistor drawing 50 mA would be desirable. Using
Ohm's Law, the resistor value becomes 2,400 ohms. This
resistor will dissipate 6 watts, so a 7.5 or 10-watt size power
resistor should be used.
William Stefan
The Basic Stamp Nut