PVEA valves in 24V micro-controller system

[SorenHPedersen]

Hi
I use a MC088 and PVEA valves in a 24V system. Unfortunately my valves some time don´t respond. By luck I found that it was the battery voltage that caused this. To high > about 25V and no respond.
After some search I now have found that I need special cables, 520L0553 • Rev GD • Jan 2014 page 51, PLUS+1® micro-controller in 24 V systems.
When and is this true?, how I modify a standard cable.

Søren

[dlewis]

We use a 24 volt system in our trucks and we don't use a special cable.  First of all be sure that your Udc pin is connected to a PVG Pwr pin on the controller.  I ran across this on a MC050-10 that we were using at the time, even though I had several units already in the field and working fine that did not use the Pwr pin.  Second, we add a 100 Ohm resister inline with the Us pin.  I don't know if this resister is required anymore, but we continue to use it.  I'd like to know what's in this special cable that your referring to.

[SorenHPedersen]

Hi

All my PVEA valves Udc is connected to PVGpwr. I will try the 100ohm with the Us.
I don´t know what in this special cables.

[BRIan]

You should refer to PIB: PV2010-009

[dlewis]

This is the text of PV2010-009

We have seen applications with PVE powered by the PLUS+1 multi function output where the system cannot work after
PVE replacement. These systems have been powered by a battery and the failure is related to the PLUS+1 MC short circuit
protection. The problem is a consequence of too low system impedance. A PVE connected directly to a battery will over a
time of 10ns draw up to 40A if there is very low impedance/resistance in the connection. The problem has not been seen on
systems running lower than 20Volt.
To eliminate the problem you can add resistance to the power line (Vbat) to the PVE. Insert a 1 Ohm resistor or smaller in
the power line. This will transfer power to heat and should only be used if the problem is present.
An immediate change to the PVE design is unfortunately not possible. By the end of this year new cables with resistance
will be available in both Deutsch and AMP versions. The PIB will be updated when the cables are released.