electric devices

[kefah]

what are the utility of those devices
1 which connected the high speed of outdoor fan speed L supply
10157


2 same type connect the contactor and L of indoor unit
10158
the system type is as below
samsung uqt24s6gea

[hookster]

They look like RC filters (low Pass), this is to prevent harmonics from the inverters.

[Brian_UK]

Sometimes used across the contactor coil circuit to prevent 'spikes' in the electrics when the coil is switched on/off.

http://uk.rs-online.com/web/p/contactor-accessories/0759128/

[Grizzly]

Sometimes used across the contactor coil circuit to prevent 'spikes' in the electrics when the coil is switched on/off.

http://uk.rs-online.com/web/p/contactor-accessories/0759128/

As Brian Say's, the problem is not so much when the contactor is de-energised, But when the contactor is disconnecting.
I am led to believe that whilst the contacts are separating there can be a huge "in-rush of current across the contacts.
These help smooth the current and therefore protect and prolong the actual contacts from damage.
Grizzly

[kefah]

thank all
you said it will prevent the sparks in the contactor
so what about the first question
which connected the high speed of outdoor fan speed L supply
http://www.refrigeration-engineer.com/forums/attachment.php?attachmentid=10158&d=1364153913&thumb=1

[alexhk]

It's the same question, isn't it? Prevents sparks so protecting equipment from damage (also prevents interference).

[kefah]

thank u all

[NiHaoMike]

They certainly look like snubber caps. I'm surprised there's no series resistor to prevent current spikes when the contactor closes, but maybe they're special ones with that resistor integrated.

Here's a snubber in one of my designs:
http://i41.tinypic.com/2utteg2.jpg
You can clearly see the resistor in series with the snubber capacitor. (That pink package is a surge protector.)

[Doug30293]

what are the utility of those devices
1 which connected the high speed of outdoor fan speed L supply
10157


2 same type connect the contactor and L of indoor unit
10158
the system type is as below
samsung uqt24s6gea


You can see from the markings on these that they are indeed RC snubbers. They are generally used across the contactor coil to prevent inductive flyback (spikes) to upstream electronics when the coil de-energizes. I use them on all contactors to prevent damage to my PLC's.

From your description I would say these snubbers are to prevent inductive flyback from the motor that causes burned contacts - same effect, different location.

Inductive spike only occurs when the coil de-energizes. (The fan motor is essentially a big coil.) The spark you see when the contacts close is actually caused by contact bounce.

[kefah]

ok
thank u all