How to reduced Contactor Spike..?

i have develop a control with vacum blower motor. it's motor shut on/off with contactor Telemechaniq LC09K. If start contactor ON, or end contactor OFF, the spike from contactor have reset a display controller.

Anybody can help me..?

Use a snubber circuit consisting of a resistor connected in series with HV capacitor, similar as used with dc motors ..

Added after 11 minutes:

Here is a link to "snubber circuits, theory, design and applications":
**broken link removed**

But the contactor have AC voltage to energized ON, is it same as DC voltage RC snubber circuit..?

I was trial to use snubber circuit wth R= 10K and C = 4n7, but it'a still have my problem.

ground the Telemechaniq LC09K mettalic part and other mettalic parts.

use (100 Ohm 1/2 W in series with 47 to 100 nF) connected in parallel with the contacts.
Usually it works good.
Mandi

some comments:

when you put it all together keep your lead lengths to an absolute minimum. i.e. solder the resistor directly to one contact's terminal, solder the other side of the resistor to the capacitor, and the other side of the capacitor to the 2nd contactor terminal.

also, keep in mind that if you mis-calculate the values for your snumbber you may infact cause resonance which will only make your arcing problem worse!

a *good* snubber design is like a fuse, they seem like very simble device - but there is a tremendous amount of technology and thought that goes into them.

you only need a *good* snubber if you are trying to pass some sort of industry standard for conducted or radiated emissions. otherwise, a standard approach is sufficient.

Mr.Cool

garg29 said:

ground the Telemechaniq LC09K mettalic part and other mettalic parts.

Click to expand...

what is mettalic part.?, where is it place.?

If it is a dc motor maybe you could replace contactor with a MOSFET switch, if it is AC you can use solid state relay .. in both cases the spike will be eliminated ..

yes IanP, I think replace this contactor with Solid State Relay, or rewrite program uC to avoid spike.
But I still want 'why reduced this spike.?'

Added after 8 minutes:

FANT said:

use (100 Ohm 1/2 W in series with 47 to 100 nF) connected in parallel with the contacts.
Usually it works good.
Mandi

Click to expand...

Hi Fant, I was trial this RC circuit, but it is still spike to my problem

hi friend i also want to connect Contactor with AVR plz help me.

Most general reasons for fails descripted are

Changes reflected to low voltage power
1. Connecting load drops 220Vac down
2. Opening inductive circuit causes voltage spike to 220Vac line

3. Motor or power wire magnetic field ???? , if there is near low voltage wires

Try following................

1. check voltage input to controller power supply with oscilloscope
-are low voltages filtering capacitances big enough ( is there hf-capacitors too )

2. add RC-supressor circuit parallel to inductive load ( parallel contactor contacts too)
-add choke coils to low power supply wires

3. Low voltage wires are too near and parallel with 220V and load wires
- bigger distance, grounded shield for low volt wires, not side by side ( parallel placed)

4. put contactor in closed and grounded iron box ( cut out magnetic field)
or put all low volt circuits in magnetic and electrical conductive grounded box

- if there is long cables for switches or buttons add 1..4.7nF capacitors to
inputs if possible ( dc-circuits )

5. All shielded cables are grounded only one end.
- all groundings are done in one point.

KAK