PVE trouble

[Jelmer]

Yesterday I had some trouble with commisioning a very simple program. The program was made for a MC24-20 controller. Designed to control voor PVG sections (all high proportional). In the program I used 4 PVE function blocks each connected to seperate multifunctional outputs for the control voltage.

For safety reasons I also controlled the supply voltage, of the valves, by the controller. For this I “or-ed” the supplies comming for the PVE driver blocks to control 2 digital outputs (2 valves for 1 digital output). When I looked at the running program in the servicetool all was working fine.

However the valves didn’t respond as expected. When only 1 valve is connected to the digital output all is OK, but when I connect the second valve, the 24 volt supply is gone. In the service tool the digital output is still “green”.

I tackeld this problem by giving every valve it’s own digital output, but this should be working. Any idea of what is going wrong?

[Slashe]

Hi Jelmer,

I guess that current peak for MF pin is too high when two or more PVE´s are activated at the same time. If you take a look of MC24-20 data sheet there is stated that any output pin should be used to power only one PVE.

[Sedov_va]

You must connect the PVE power supply through a relay.

[Volker]

We had a similar problem. When you use a PVG-Power Output you can supply three PVE's. With a normal Output you can supply only one PVE.

[Jelmer]

I'm using C2p3 and C2p4 so in theory I can supply 3 PVE simultanious....but still no result :-(

[Slashe]

There are no PVG Power Outputs in MC24-20. There are only MF outputs. With Multifunction output you can only supply one PVE. Take a look of latest data sheet.

[Neil]

Jelmar, are you using a MF function block on the C2P3 and C2P4?
Have you added a check point to the "pin status" for C2P3 and C2P4?


Neil.

[Eduardo Siqueira]

Good afternoon,
I wonder if someone already made some scheduled for crane coletamoos need that part where the transmitter signal. I need the formula.
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[Marbek_Elektronik]

A long time, it was possible to drive 3 PVEs with Pin c2p3 or c2p4.
then they changed a input capacitor in valves: maybe from 100nf to 1 or 2 µF.
So my application which worked with older PVEs doesn't work now with more than 1 PVE.
I think, they now use 100nF.
But the problem is, there are PVEs with larger input capacistance, so you can only drive one PVE.
I have a special application: I put one diode from each neutral-switch to the valves.
So, the joystick power the valves. Then the controller power on the valves.
In my application, there is no danger of backward current in outputs. So it works!

[mebib]

You can put a 1 ohm- resistor in series to the supply pin of each PVE. This will reduce the peak current during turn on and it should work with a MFOut. There are special cables available @ Sauer-Danfoss with this resistor build in. Contact your dealer for details.

[Jelmer]

Thanks you guys, this problem is long being solved (=worked around). funny that no one from Sauer Danfoss came up with this when I had the problem. It's good to  know for the future.

[Marbek_Elektronik]

Is there only 1 Resister in the cable or 2?
Because the signal have to be in the middle of the power supply, for example 6V by 12V system.
If you have 1Ohm in series you there is a loss of voltage of o,7V (1R , 0,7A)
So there is 11,3V. But the signal is 6V. So it is 53% of voltage.

If there is another Resistor in negative supply voltage, you get
0,7V and 11,3V at the valve and the 6V signal is in the middle.

If you have 24V, my idea is to switch all 6 valves with 1 Output and a resistor!
After a short time, you switch a second port in parallel with no resistor to drive all 6 valves.
This only works by 24V because of the smaller current.