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### Topic: SSR - zero cross trigger (Read 2563 times)previous topic - next topic

#### LionHeart

##### Dec 07, 2012, 04:27 am
hi there i am new in the community, sorry for my english.

i just read this topic http://arduino.cc/forum/index.php/topic,10437.0.html and i learn a bit about SSR with zero cross trigger  as control method. Well here is the question i want control a water-pump ( 13A, 60Hz , 1HP,... ) and 2 exractors ( each 6.6 A  ) from this http://www.fotek.com.tw/pdf/etc_33.pdf  i chose a SSR-25DA model, but i am just 95% sure  about buy this, and i want be 100%. Can u tell me if i can control turn on/off the water-pump and the extractos with 2 SSR-25DA  when i want from my arduino MEGA???  and what about this  zero cross trigger method how many dealy will cause?? i read this method is for protection.

#### jackrae

#1
##### Dec 07, 2012, 12:55 pm
These should meet your need - but there is no guarantee.  The delay will be a maximum of one half cycle, so at 60Hz this would be around 0.008seconds.

#### LionHeart

#2
##### Dec 07, 2012, 01:55 pm
hi there thx for reply what u mean with no guarantee ? , i mean i need to know jejejej, and how u calculate the dealy

#### jackrae

#3
##### Dec 07, 2012, 02:21 pm
By "no guarantee" I mean I have given you my opinion only.  As writers on this forum we only give opinions - most, hopefully, are technically correct but occasionally some are incorrect.

The device operates at zero cross-over point.  In any full cycle there are 2 cross-overs, 0 degrees and 180 degrees.  Assuming your trigger has just missed a cross-over, the turn-on will not occur until the next one, which will be just under one-half cycle into the future.  At 60Hz the period is 1/60seconds = 16.666 mS, so 1/2 cycle period is 8.333 mS.  Hence, if you just miss a cross-over point, the next one will be a maximum of 8.333 mS away (ie the delay time)

#### dc42

#4
##### Dec 07, 2012, 07:00 pm
Inductive loads such as motors and probably your pump should be controlled by random-fire SSRs, not zero-crossing ones. A zero-crossing SSR feeding an inductive load will turn off prematurely part way through each half cycle of power.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

#### LionHeart

#5
##### Dec 08, 2012, 01:49 am
dam  , i just bougth one SSR-25DA , so it will not work  for the water pump ?    maybe can work both extractors?, or one at least? (each extractor work with 6A),  :? ,

#### dc42

#6
##### Dec 08, 2012, 09:54 am
It might work, it depends on how inductive the water pump is. If it doesn't, try connecting a 100W incandescent light bulb in parallel with the water pump and see if that improves things.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

#### LionHeart

#7
##### Dec 11, 2012, 02:09 pm
well thx the ssr is in coming soo y will test, maybe if i give all the info about the water pump and extractors u can said more about the inductive thing?

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