To start/stop energizing the heating elements there are used two buttons, each with a NO and NC contacts. The push buttons have LED lights (a max of 15 mA). There is a set of power contacts, for the heaters, that are driven by a coil (240Vac), CR1. The start button will actuate the coil, the stop button will interrupt the heating. The general 240Vac supply is separately provided.
There is only one low power NO contact, physically connected on the contactor driven by CR1 (besides the power contacts).
There are not other contacts to be switched by a coil.
Stop red button is glowing while the heaters are not energized.
Start green light will glow when push button start is pressed.
With only NC NO contacts, stop button light cannot be cut.
There is a way, connecting stop button LED combination between L1 the CR1 coil and L2.
It works, I tried several times. What would be the CONS to this wiring?
L1 LED coil (800 Ohm) L2
X-------------XX--------------------xCR1x----------------x
The LED 15 mA are more than an order of magnitude less than the necessary current to the coil to be energized, and the drop of voltage on the coil is less than 15V, so the voltage on the LED still, would be over the minimum of 195Vac, necessary to lit the light.
There is only one low power NO contact, physically connected on the contactor driven by CR1 (besides the power contacts).
There are not other contacts to be switched by a coil.
Stop red button is glowing while the heaters are not energized.
Start green light will glow when push button start is pressed.
With only NC NO contacts, stop button light cannot be cut.
There is a way, connecting stop button LED combination between L1 the CR1 coil and L2.
It works, I tried several times. What would be the CONS to this wiring?
L1 LED coil (800 Ohm) L2
X-------------XX--------------------xCR1x----------------x
The LED 15 mA are more than an order of magnitude less than the necessary current to the coil to be energized, and the drop of voltage on the coil is less than 15V, so the voltage on the LED still, would be over the minimum of 195Vac, necessary to lit the light.