Interference

From Coil 12V

The 12V for the ignition is normally controlled from a key on the dashboard. This is not recommended since the cables that supply 12V to the coil or motor ignition cause interference that can affect the measurement or cause communication interruptions in the USB cable.

The interference from the cables carrying the pulsating coil current is greater the longer these cables are. In addition, these cables have to be thick since they carry a high current.

It is necessary to eliminate these cables since they are long sections and also they pass very close to the PC and the signal cables.

The best way to reduce the interference generated is by mounting the battery close to the panel where the coil and engine ignition will be. That way the wires will be closer.

In order to switch the ignition from the control panel, an automotive relay must be installed in the panel near the engine. The contact key that commands this relay can be of low amperage and the installation can be done with low section wires, since it only carries current from the relay coil.

WIRELESS PROPAGATION

Electromagnetic interference propagates through the air. Its intensity decreases with distance.

High voltage from spark plugs

High voltage spark plug wires also produce electromagnetic interference. In this case the solution is to avoid using copper wires and always use EMI suppression spark plug wires.

Switching current from electric motors and solenoid valves

Three-phase motors, solenoid valves, and other inductive loads produce a current spike during on or off switching. This current when circulating through the cables that go to the load, which can be a motor, a pump, or an electrovalve, can generate electromagnetic interference or even cause problems in the room´s electric wiring.

That interference can even come from motors elsewhere in the room, such as starting an air compressor in another part of the shop. If the PC and system cabling share electric wiring with other loads, there may be an effect on the measurement. It all depends on the wiring, such as the section of cables in the workshop.

SPREAD THROUGH THE ELECTRICAL NETWORK

Conduction interference propagates through the cables. They can affect long distances, depending on the electrical wiring.

To avoid interference in the electrical network, take into account the following:

• Move the interface and USB measurement cables away from the mains cables that supply current to pumps, motors or solenoid valves.
• In case of interference from any element further away, it may be due to a bad electrical network. In that case you will probably have to bring a dedicated power line for PC and acquisition system.
• We recommend having a dedicated ground rod for the interface and PC.