Reading the Circuit diagram of a Safety switch( RCU) 1

[joji90]

Hi All,


can anyone help me read this circuit diagram for a remote control unit of a motor . excuse me for being a noob! I'm from instrumentation background.

thanks in advance,
joji

 

[che12345]

Dear Mr.joji90 (Petroleum)(OP)11 Feb 22 09:08
[COLOR=]"... can anyone help me read this circuit diagram for a remote control unit of a motor..."[/color].
1. I noticed that this V2 diagram differs from the V1 posted earlier. I try to answer based on V2 diagram.
2. Some basic info:
a) diagram on the left hand side is the "development" diagram. A crossed square means contact is close. e.g. see (1) at 45deg labelled I, contact 1-2 is close. Contact 3-4 is open. At 90deg labelled 0 , contact 1-2 and contact 3-4 are open. At 135deg labelled II, contact 1-2 is open, but contact 3-4 is close.
3. Now see (2):
a) at 45deg contact 1-2 and 3-4 are open. At 90deg contact 1-2 is open bur contact 3-4 is close. At 135 deg contact 1-2 and contact 3-4 are close.
b) attention: see at 90deg and 135 deg showing contact 3-4 are close with a link. The link means that while rotating from 90deg to 135 deg, contact "over-lapped" i.e. contact 3-4 remain close until 135deg position.
4. In usual case, while rotating, a closed contact opens fully before the other open contact close i.g. NO over-lapping.
Che Kuan Yau (Singapore)

 

[joji90]

Hi Che12345

thanks a lot for your response, this info I couldn't find anywhere online . I removed the first picture because the vendor confirmed that the development drawing was wrong, hence I replaced with this one.

So in fig(2) ,just to clarify more,

1.)what is the significance of I ,0 and II mentioned on 45,90 and 135 respectively?


2.) unlike normal operation of opening a contact while moving the position , the overlapped means the contact at 90 stays close until the moment 135 is engaged which closes 3 and 4 and only then opens 1 and 2. Please correct me if I'm wrong

3.) what is the significance of showing some contacts NO and NC on the right hand side when crossed square on the development drawing always means close?

Thanks and Regards,
Joji

 

[che12345]

Dear Mr. joji90 (Petroleum)(OP)14 Feb 22 09:14
"... 1.) so in fig(2) ,just to clarify more,
1.)what is the significance of I ,0 and II mentioned on 45,90 and 135 respectively?..."

# 1. In (1) the switch is labelled I 0 II where 0 with both contacts 1-2 and 3-4 are open. in I contact 1-2 close, which switches on circuit say A. In II contact 1-2 open i.e. switch off circuit A and contact 3-4 closed to switch on circuit B. At 0 both circuits A and B are off.
Now see (2) At 45deg labelled 0 , 90deg not labelled and 135deg labelled I. The switch is either at 45deg or 135deg, it does NOT stop at 90deg. At 0 contacts 1-2 and 3-4 are open. When rotate from 45deg , at 90deg contact 2-3 close and maintain close until the switch stopped at 135deg. At 135 deg, contacts 1-2 and 3-4 are close.

"... 2.) unlike normal operation of opening a contact with .. moving the position , the overlapped means the contact at 90 stays close until the moment 135 is engaged which closes 3 and 4 and only then opens 1 and 2. ... if I'm wrong"

No. At 0deg contact 1-2 is open. When rotating from 0deg , at 90deg 3-4 close and remain close when the switch stopped at 135deg. When the switch reached 135deg , contact 1-2 close.

"... 3.) what is the significance of showing some contacts NO and NC on the right hand side when crossed square on the development drawing always means close?.."
In simple configuration, the right hand side conveys the operation. However, some more complicated switching functions, the development diagram enhances the contact function with better detail. BTW the square NOT crossed = contact in open status.
Che Kuan Yau (Singapore)

 

[joji90]

Dear Che12345,

Perfect, thank you so much.

One last question, I have another RCU where contacts are marked Z1/Z2 instead of 1 and 2. what does Z prefix mean?

Thanks and regards,
joji

 

[che12345]

Dear Mr. joji90 (Petroleum)(OP)18 Feb 22 08:02
[highlight #204A87]"... One last question, I have another RCU where contacts are marked Z1/Z2 instead of 1 and 2. what does Z prefix mean?... "[/highlight]
1. Sorry, I do Not know why or the significance of the prefix Z.
2. Guessing: May be the switch terminal 1-2 is labelled Z!-Z2 ?
Che Kuan Yau (Singapore)

 

[joji90]

Dear Che12345,

thanks for your time,
the old Motor loop drawings from the plant I'm working on has RCU represented differently, I'm trying to figure out that how it works, any help is appreciated.
please see below:

Please excuse me for being a noob in electrical engineering!

Regards,
Joji