In electrical engineering, two conductors are said to be inductively coupled or magnetically coupled when they are configured in a way such that change in current through one wire induces a voltage across the ends of the other wire through electromagnetic induction.

IBTL

 

This is true for AC not DC correct?

^^^Answered by Paul

 

It's normal if you're using a basic digital meter. The input impedance of such a meter is around 11 meg-ohms and it'll read inductive and/or capacitive coupling to energized conductor.

This is often called a 'ghost voltage', the current is very low.

 

It's normal if you're using a basic digital meter. The input impedance of such a meter is around 11 meg-ohms and it'll read inductive and/or capacitive coupling to energized conductor.

This is often called a 'ghost voltage', the current is very low.

When the magnetic contactor picks up (for valve opening or closing), then induction voltage does'nt allow it to drop out. Hence the other operation is blocked. Seperate cables have been used for motor power circuit)

 

Well this seems like a good post

 

It’s capacitive coupling. Capacitance is two conductors separated by an insulator. Induction is usually more of a complete circuit/loop.

It easily shows up with a multimeter as described but also many control system inputs (PLC inputs) are fairly high impedance. A common inductive problem with motor circuits is this. Say you run a single 7 conductor cable out to a remote pumping station. Four (3 conductors plus ground) are for the motor. Control power is on another and the last two return “start” and “stop” signals. So what often happens is once the motor starts it inductively couples enough voltage onto the “stop” signal (normally closed logic) that the motor will not stop because the PLC input is continuously energized regardless of the status of the button.

This points out two things. First use DC control signals and this sort of thing won’t happen. There are many advantages of DC control over AC and this is a major one. Second route the control and power in separate raceways or at least separate cables. It may be “ghost voltage” but under some fairly common situations those ghosts become real.

 

If your having problems with micro relays from the eddy currents being induced use a ice cube relay or a rib something with an actual coil in series before your micro relay.

 

You are going to have a make a sketch and post it.

you start by saying only 2 core are used for indication then you say that they hold in a magnetic contactor.

If you are in fact used multiply cores and the valve indications are incorrect due to induced voltage then simply add a relay. If you are saying that induced voltage is holding in a contactor then its time to test the wire because that's not happening.

 

You are going to have a make a sketch and post it.

you start by saying only 2 core are used for indication then you say that they hold in a magnetic contactor.

If you are in fact used multiply cores and the valve indications are incorrect due to induced voltage then simply add a relay. If you are saying that induced voltage is holding in a contactor then its time to test the wire because that's not happening.

you misspelled "ibtl"