basics

laura_jenny · Oct 7, 2012

thnks for ur help i have started learning
can u say simple words where to use NO and NC
this is bit confusing me normally open means its high curent will flow,
normally closed means current will stop no current will flow .so can any one explain it when to use and when not to use
thnk u

sthompson · Oct 7, 2012

I highly recommend you watch Ron Beaufort's sample lessons.

They will answer many of your questions.

http://www.ronbeaufort.com/sample_lessons_for_frame.htm

Stu....

nettogrisen · Oct 7, 2012

When dealing with electrics you should always consider the term "closed" as current flowing through the contact.
At least I can't think of an example of the opposite.

iant · Oct 7, 2012

when power is switched On to a device the devices state can change from either On to Off or Off to On.
this is where the names of NO or NC originated from.
it is the state of a device with the power normally OFF or when the device is physically released or Free from operation.
You will hear the AB terms of XIC or XIO (NO and NC respectively)
this is specifically internal PLC programming, not external devices.

GlennA · Oct 7, 2012

When a water faucet is open, water flows. For electricity, a closed circuit is a complete loop and allows current to flow. The basics of PLC programming is relay logic. Start with some basic electrical circuits and relay circuits.

L D[AR2P#0.0] · Oct 8, 2012

Late on a Saturday night - Kebab shop normally open, public library normally closed.

laura_jenny · Oct 8, 2012

thnk u i got u

Lancie1 · Oct 8, 2012

it is the state of a device with the power normally OFF or when the device is physically released or Free from operation.

At one time, "with the power normally off" would have been a definitive condition with no way to misinterpret the meaning. Now that are solid-state devices (relays and timer relays) that have four different power states: control power on or off, and signal-switch power on or off. Some manufacturers have started defining a case with control power on and signal-switch power off to be the same as the old "power normally off" state. This is where specifications become confusing and errors creep in.

iadapt · Oct 8, 2012

Great explanation Lancie1, thanks.

arkyny · Oct 9, 2012

Easy for you Lancie, probably not for her. Open, nO flow, Closed, Current flow, 2 bits heah

laura_jenny · Oct 10, 2012

now i have got good idea on timers counters and maths functions
when we have to use user defined tags
and add on instruction

Lancie1 · Oct 10, 2012

Easy for you Lancie, probably not for her. Open, nO flow, Closed, Current flow, 2 bits heah

I would not ever use those terms to describe the terms "normally open" and "normally closed". I think trying to put those in terms of current flow is a big mistake for any student.

This is a bit confusing for me: normally open means its high curent will flow, normally closed means current will stop (no current will flow)

Laura-jenny, I can see that would be confusing because your description is EXACTLY BACKWARDS to the real true original meaning of NO and NC. For a NO switch or contact, no current CAN flow because the current path is open, and for a NC switch, current can flow through a closed path.

Now for the equivalent PLC instructions that read input signals into PLC memory, that is a different story and should NOT be confused with "NO" and "NC". They are two different concepts or functions. Trying to make the two things equal is like saying apples and oranges are equal.

ydtech · Oct 10, 2012

Laura,

You have started at least three threads titled "basics", this gets to be a bit confusing. How about choosing one of them and tack all your posts to it?

Lancie1 · Oct 10, 2012

How would a beginner know the tremendous amount of stuff that has to be a part of the Basics foundation? As long as she doesn't get into "Advanced", we are good to go!

rta53 · Oct 10, 2012

If you want to see confused, try explaining to a green electrician the logic of a NO relay connected to a NC solenoid supplying air to a NC actuated valve that is operated by pressing a NO push button.

basics

laura_jenny

Member

sthompson

Lifetime Supporting Member + Moderator

nettogrisen

Lifetime Supporting Member

iant

Lifetime Supporting Member + Moderator

GlennA

Member

L D[AR2P#0.0]

Lifetime Supporting Member

laura_jenny

Member

Lancie1

Lifetime Supporting Member

iadapt

Lifetime Supporting Member

arkyny

Member

laura_jenny

Member

Lancie1

Lifetime Supporting Member

ydtech

Member

Lancie1

Lifetime Supporting Member

rta53

Lifetime Supporting Member

Similar Topics