Surge protection in trucks

[atoft]

Does anyone know if it is normal to protect electronic circuits in a truck against spikes/overvoltage?

I want to mount a pressure transducer with max. voltage 30V in a truck with 24V battery.

What spikes must you expect to find in the electrical system in a truck (what voltage level)?

How would you normally protect electronics against high voltage in a truck?

Allan

 

[ruggedscot]

This is a regular one this. First you need to find out just what the electrical ratings of the sensor is, if its auto/truck rated then it will have the required filters inbuilt if not then the easiest way is to make up a simple voltage limit circuit, comprising of a diode resistor zener diode and capacitor, really quite a simple circuit but you need to know power requirements of the device being supplied. Then you have the problems of the cable connecting whats being monitored to whats doing the monitoring, this can pick up interferance if not properly run.

The zener will limit the surges that you get when the alternator is charging the battery and of course when you are cranking the engine you will get some pretty serious dips and spikes in the suplly as the commutator in the starter does its stuff.

Rugged

 

[Comcokid]

Vehicle electrical systems do have transients. OEMs making devices usually test to SAE J1113 which describes the various transients that may happen, and sets a standard for testing. Collectively, the term used frequently is "Load Dump" to refer to the transients, but technically, Load Dump is a specific type of transient dealing with the alternator. This term makes for a good starting point for a search.

Once recent thread "Voltage Clamp" thread240-98170 , dealt with the issues on a 12volt system. The same basic issues apply to 24 volt systems.

OEMs must protect from all the various problems that may occur over the life of a vehicle. If you are doing a one-off installation, you might risk less protection. If your transducer will operate at less than 24 volts, then use a regulator ahead of it (i.e. a LM317, or LM317HV) set to a slightly lower voltage.