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Re: [RFI] Galaxy Grow Light Ballast Update

To: jim@audiosystemsgroup.com, Rfi List <rfi@contesting.com>
Subject: Re: [RFI] Galaxy Grow Light Ballast Update
From: Tom Thompson <w0ivj@tomthompson.com>
Date: Tue, 2 Feb 2016 16:55:13 -0700
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
I did an LTSpice simulation of switching 120 volts through a 600 uH inductor into an 8 ohm load. The inductor delays 30 amps of current through the load by 600 microseconds and 15 amps by 200 microseconds. Even with the fast switching speed of a magnetic breaker, the delay is insignificant. I think the best magnetic breaker switches in about 3 milliseconds.

Also, the human body will never draw enough current to flip a normal breaker. On the other hand if a person touches the hot wire of a GFCI protected circuit while in contact with a ground, the person will unbalance the current in the hot-neutral circuit and trip the GFCI if the current imbalance exceeds 10 to 20 milliamps. This protects human life.

Tom   W0IVJ

On 2/1/2016 2:58 PM, Jim Brown wrote:
On Mon,2/1/2016 1:19 PM, Tom Thompson wrote:
I respectfully disagree. The choke in the green wire and the common mode choke both are 300uH. A short circuit current between the hot and the green wire would pass through both chokes in series. At 60 Hz the total impedance is 0.2 ohms which is not going to affect the breaker or fuse blowing.

But it's NOT 60 Hz, it's an impulse. And if the choke is effective at killing RFI, it's got significant resistive impedance at the frequencies of that impulse.

The question is not WILL it blow the fuse/breaker, but will it blow FAST ENOUGH to protect someone from electrical shock.

73, Jim
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