retaining contact

emeka · Dec 23, 2012

hi frnds,pls can someone tel me how to retain contact on a relay.....for example pushing a botton to activate a bulb,and d bulb stil stays on even when the botton is released..

BobB · Dec 23, 2012

A self latching circuit - and then you need to utilise something else to unlatch the circuit - this is really simple control logic.

Bob O · Dec 23, 2012

Welcome!

Search the forum for a seal in or start stop. How do you plan to turn this bulb off once it is turned on? Also, what PLC are you using?

HTH

emeka · Dec 23, 2012

thanks bob,but am not actually using a plc..i am tryin 2 construct a water level control using relays and flot switches

DamianInRochester · Dec 23, 2012

Unlatch Latch R1
|------|/|------------| |------------------( )--|
| |
| R1 |
----| |----

DamianInRochester · Dec 23, 2012

.....Unlatch..........Latch.....................R1
|------|/|---------| |------------------( )--|
...................|..............|
...................|...R1........|
...................----| |----

Here's another try

emeka · Dec 23, 2012

thanks,i guess i just have 2 try it out,i'll get bak 2 u if am stil having challenges wit it..

emeka · Dec 23, 2012

am talkin of a water level control to be precise..and its gona comprise 2 flot switch nd a 3pole relay...ow it works?flot switch A wld be placed at d lower part of the tank,while flot switch B wld be placed at the upper part of the tank.1,flot switch A and flot switch B has to make for the pump 2 work.2,flot switch A and B has 2 also make for the pump 2 stop working...its not 2 be done wit a plc,just relays

daba · Dec 23, 2012

Does the pump Fill, or Empty, the tank? It is not clear from your description.

iant · Dec 23, 2012

the problem is that the graphic symbols are the same as PLC Code.

so lets talk about your wiring
1. LOW LEVEL FLOAT SWITCH
- requires to START the PUMP when actuated.
(Normally Closed Contact - Held OPEN by the water)
- CALL THIS ONE 'A'
2. HIGH LEVEL FLOAT SWITCH
- requires to STOP the PUMP when activated.
(Normally Closed Contact - will OPEN by the water at the height set.
- CALL This One 'B'
3. MOTOR CONTACTOR OR RELAY
- to supply power to th pump
- CALL This One 'C'

     A           B                 C

!---]/[----!----]/[---------------( )--

!          !

!    C     !

!---] [----!

OkiePC · Dec 23, 2012

Hey guys, try wrappering your ladder pictograms with the code or ladder tag:



         Start              Stop

         PB1                PB2              MyLampBit

-+-------]  [-------+-------]  [---------------(   )----------+

 |                  |                             

 |                  |                             

 |                  |                             

 |                  |                             

 |    MyLampBit     |                             

 +-------]  [-------+

Use the word ladder or code enclosed in square brackets, to end that style, use the same preceded by a backslash. This prevents the forum from trimming up your whitespace (removing redundant spaces).

krakenfan69 · Dec 23, 2012

Are you saying that you are opening and closing a 3 pole relay to control power flow to the
motor? What size motor are you controlling this way. Is is just a relay or an actual motor starter? A 3 pole relay will not give you thermal protection for your motor. a motor starter with properly sized thermal protection (heaters or overloads) are cheap insurance against single phasing and burning up a motor. Then you have the downtime to replace the motor plus the lost product to consider as well. Food for thought.

Kraken Fan #69

iant · Dec 24, 2012

OkiePC said:

Hey guys, try wrappering your ladder pictograms with the code or ladder tag:



         Start              Stop

         PB1                PB2              MyLampBit

-+-------]  [-------+-------]  [---------------(   )----------+

 |                  |                             

 |                  |                             

 |                  |                             

 |                  |                             

 |    MyLampBit     |                             

 +-------]  [-------+

Use the word ladder or code enclosed in square brackets, to end that style, use the same preceded by a backslash. This prevents the forum from trimming up your whitespace (removing redundant spaces).

i'll try that
but can you redo it the same format as mine
(N/C contqcts for the float switches

OkiePC · Dec 24, 2012

iant said:
i'll try that
but can you redo it the same format as mine
(N/C contqcts for the float switches

sure

OkiePC said:

DamianInRochester · Dec 24, 2012

That's my "something new learned today".

Thanks Paul.

retaining contact

emeka

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Bob O

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emeka

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iant

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