can sombody review and coment my design

hello
i am not a designer but i have my experiance in repairing stuff and hobbying

i design this to swich 2 transfer pumps that work on fixed time alternating

design criterias are keep it simple cheap and foolproof

an other problem i have here in cambodia is that components are very hard to get by

as you can see in the shematic i made an analoge AND port with 4 inputs
normaly i would use the 4082 but is not availible here

i prefer to use triacs because 220V contactor blocks are the only one that are on the shelf here otherwise 24V i have to order them and wait 4 weeks to get them, not good if one break down and you have to replace them right away

thanks in advance
Robert-Jan

hi,
I am having problems opening your pdf.

Anyone else been succesful?

EDIT:
Had to download an extension to my Foxit pdf reader.. now OK.

hi Robert-Jan,

Looking at the circuit, it has a number of serious errors and omissions.

For example:
the zener diode has no current limiting resistor.
the mains transformer is connected so that you have no isolation.
[the Neutral phase is connected to the 0V/common line]
etc.....

The right side of the drawing is cut off?

EDIT:
Are opto-isolators available in your region??

didn't came across a oupto coupler yet in cambodia
bangkok is the closest place to get them but that trip i make only 2 times a year

the reason the nuetral is conected to the 0V line is to get the triacs working

right side of the drawing is only the capacitor + resistor to protect the voltage spikes over the triac

the whole PCB and its conections will be in a IP 53 housing in the swich panel what also is rated for IP 55

did made some changes regarding the current limiting resistor

i could made some changes in the contactors (24Volt ones ) so i don't have to use triac and i could go for a FET (IRF 510) and change the whole power suply to 24V dc

the thing is that the contacters will cuase problems over a timespan of 2 years due to the agrasive envoirment they are placed in

troppics ,high humidity pump room , and chlorine fumes (swimming pool pumps)
and a sudden brakedown of a contactor have to be tackeled by replacing it imedietly and preferbly the other ones in the panel also

220V in store 24V lead time of 4 weeks