Where and how is this stray voltage created? Is there a simple solution to squash it? It is causing the LEDs to illuminate faintly even with the main switch S1 OFF.
Here is a diagram of the situation. 2 legs of the 3-phase mains runs to the primary of a stepdown trnsformer; the 120vac secondary has one side tied to chassis that is tied to Prot. Earth Ground back at the 3-phase mains box.
The 120 V LEDs used in the bulb sockets don't measure any voltage drop, but will very faintly illuminate with a DMM diode check. With the bulbs out i read about 10vac as shown from the downstream side of S1 to GND. With bulbs in it drops as shown.
i've read about capacitive coupling, but don't understand where it occurs or how to eliminate it. i need some clues to this mystery.
Here is a diagram of the situation. 2 legs of the 3-phase mains runs to the primary of a stepdown trnsformer; the 120vac secondary has one side tied to chassis that is tied to Prot. Earth Ground back at the 3-phase mains box.
The 120 V LEDs used in the bulb sockets don't measure any voltage drop, but will very faintly illuminate with a DMM diode check. With the bulbs out i read about 10vac as shown from the downstream side of S1 to GND. With bulbs in it drops as shown.
i've read about capacitive coupling, but don't understand where it occurs or how to eliminate it. i need some clues to this mystery.
Attachments
-
173.7 KB Views: 13