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Need some help with Wiring Schematics

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Need some help with Wiring Schematics

Unread postby mreccentric » Fri Mar 2, 2018 11:03 am

Hello Everyone, Good Morning!
I'm new to this, and am trying to learn things slowly but effectively. I need some details that can make me understand about schematics and circuits thats mentined below. Will be great if we can discuss on the same. Firstly, i need to understand the basics of RRI, rather than dealing with the exact operation of the diagram below. Any books for suggestions is welcome. Thanks in advance.

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Re: Need some help with Wiring Schematics

Unread postby S&TEngineer » Fri Mar 2, 2018 2:11 pm

Welcome to the forum. First question is where did you get the circuit extract from?
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Re: Need some help with Wiring Schematics

Unread postby mreccentric » Fri Mar 2, 2018 2:20 pm

Thanks for the reply. I found it in one of the manuals for Railway Signaling.

I'm finding it difficult to understand the concepts, as there were no explanation in the manual for the various circuits. I can give you the link. It comes in the first page of the google search.
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Re: Need some help with Wiring Schematics

Unread postby Mike Hodgson » Fri Mar 2, 2018 6:51 pm

Books that you would find useful are the Britisdh Standard BS 376, published in two thin paperback volumes. From time to time these come up (usually separately) on ebay and the like.
Also the "IRSE green books"

The standard uses letters to give a generally understood meaning to the various components of the system - anything ending in R will be a relay, and beginning with W means points.
For example WLR means a points control relay, and 101 WLR would mean it applied to 101 points. This circuit needs the TRSRs for both 101A and 101B to have picked, and typically 101A and 101B would the two points in a crossover. You should have a layout plan with the circuits which indicates what's what on the ground.

The symbol you ringed is a TOP contact, known in other branches of engineering as NO.
The arrow would be below, pointing upwards for a NC or BOTTOM contact.
This nomenclature might not be acceptable in general engineering, but railway signalling relays are always mounted the right way up, so bottom does mean its not-operated state.'
Other considerations (number of contacts, speed of relay operations etc) are governed by the specifying the model of relay used.
Other standard symbols are used for things such as contacts on lever frames.

Circuits are conventionally drawn in lines from left to right, the left hand end being the power supply, generally a bus bar, and the right hand end being its return. The equipment at the right hand end is what this particular circuit operates, represented as a box rather than the electrical engineer's practice of showing a coil. This style is very helpful because it shows exactly what is needed to feed the coil of 101WLR and cause it to pick up. What that relay does is for other parts of the circuit diagram, though the standardised names give you a very good clue. It makes it a lot easier for a technician to fault-find, as he knows from experience whether he expects a given relay to be up or down in a given situation. If that relay hasn't picked up when it should, he will look at the other relays shown on that circuit to see whether they have also picked.

It would be usual for the voltage to be shown, for example B24 would indicate the Positive terminal of a 24vDC supply, returned to N24. B for Battery, but the codes are not that simple to learn, as we have only 26 letters to cover rather more meanings - eg a BSR would be a Block Stick Relay. Several different voltages are commonly used for relay coils.
An AC supply would used the same letters with an X suffix (BX110 with NX 110 for a 110vAC supply).

Obviously there must be similar circuits showing what causes each of the other relays the pick up.
Similarly presented circuits will be used for a point motor or the bulbs in a signal.

Whether a particular circuit requires a top or bottom contact is usually determined by requirements for fail-safe.
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Re: Need some help with Wiring Schematics

Unread postby S&TEngineer » Fri Mar 2, 2018 7:23 pm

...err. Railway signalling relay contacts are known as FRONT (made when the relay is energised) and BACK (made when the relay is de-energised). TOP and BOTTOM are terms that haven't been used for a long number of years.
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Re: Need some help with Wiring Schematics

Unread postby Mike Hodgson » Fri Mar 2, 2018 7:52 pm

Indeed. BS 376 has been around for a lot longer than the relays in use today. Relays used to sit on shelves.
Modern relays are fitted in racks so oriented that the contacts are vertical.
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Re: Need some help with Wiring Schematics

Unread postby baconandeggs » Sat Mar 3, 2018 2:27 am

mreccentric wrote:Thanks for the reply. I found it in one of the manuals for Railway Signaling.

I'm finding it difficult to understand the concepts, as there were no explanation in the manual for the various circuits. I can give you the link. It comes in the first page of the google search.


I am not a signal engineer but do have an electrical engineering background. I find the terms up, down. front, back, picked confusing so I drew two diagrams to help *me* understand the concepts. The diagrams can be viewed at

http://valleysignals.org.nz/petone/circuitsymbols.html

Shelf relays are still very much in use near where I live (in NZ). See

http://valleysignals.org.nz/petone/petonerelayroom.html

The interlocking shown in this page has been replaced by a CBI but there are two interlockings nearby that still use shelf relays.
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Re: Need some help with Wiring Schematics

Unread postby mreccentric » Sun Mar 4, 2018 3:18 am

I read the above posts, and has been helpful to me. I wish i could hit the 'like' button, but there is no such options. But, i still have some questions, which needs to be clear to get a better clarity.

B24 and N24 are connected only to the coil?
To what are the contacts(terminals of switch) of the relay connected to?
How many coils are used in the above diagram (in the first post)? Below diagram shows only one coil.
Where are the switches/knobs/buttons used by operator used in the diagram?
What signals do relays carry?

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Re: Need some help with Wiring Schematics

Unread postby Chris Osment » Sun Mar 4, 2018 10:16 am

The original diagram essential shows two versions of a circuit. Each version has one coil 101WLR.

The coil would be fed from B24, via all the various contacts shown, across to N24.

The diagrams show the circuit(s) to operate the coil for 101WLR. The contacts worked by 101WLR would shown in the diagrams for whatever different circuits they form a part of.

Physical switches etc would not be shown, only their contacts listed.

I don't understand what is meant by "...only one coil is taking care of all the relays..."? With respect, I begin to suspect a fundamental misunderstanding of what the diagram shows.
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Re: Need some help with Wiring Schematics

Unread postby Andrew Waugh » Sun Mar 4, 2018 10:25 am

Ah, no. If I understand your diagram, I think you've completely got hold of the wrong end of the stick. No wonder you are confused.

The original diagram shows two circuits. The first runs from positive power supply, through a selection of relay contacts (of *other* relays - 101TRSR, 101BTRST, ... 101BT), to the coils of a relay (101WLR), and finally to the negative. The second is exactly the same, except it has different relay contacts.

Signalling circuits are logic circuits. The circuit diagrams are designed to show, very clearly, under what conditions a controlled object (usually a relay) will be energised.

So the circuits show a controlled object (the rectangle at the right). This is usually a relay, so you can think of the controlled object as a relay coil. The circuit leading to the controlled object shows the relay contacts that must be closed in order to energise the controlled object, and whether those other relays are energised or not.

In signalling work, the relays (and their contacts) are systematically named. The label above each contact (e.g. 101ATRSR) is the name of the relay to which that contact belongs. The label on the controlled object is the name of that object (i.e. relay) (e.g. 101WLR). (Although it's not relevant, to give you an idea, 101WLR is the Points Lock Relay (WLR) for Points 101, 10ASR is the Approach Stick Relay (ASR) for signal 10, and so on... If you know the naming convention and are familiar with the circuit principles, it's quite easy to read a fragment of a signalling circuit.)

To be quite specific. In the first circuit, in order for relay 101WLR to be energised, relays 101ATRSR, 101BTRSR, 4/6/8ASR, 10ASR, c10ASR, 101AT, and 101BT must all be energised. In the second circuit, in order for relay 101WLR to be energised, relays SMR, C01ASR, 1ASR, 11ASR, 4/6/8ASR, 10ASR, c10ASR, 101ATPR, and 101BTPR must be energised, and relay 2DR must be de-energised.

The relay contacts in the circuit show whether the relay needs to be energised or de-energised to complete the circuit. A contact of a relay that needs to be energised has the V symbol *above* the line. Think of the line as the armature, and the V as the contact. The relay has been energised and the armature has been lifted up to make the contact. A ^ below the line represents a contact that is made when the relay is de-energised.

The symbol above the line represents (in other electrical engineering disciplines) a normally open contact, below the line, a normally closed contact. These terms are not used in signal engineering because the term 'normal' has a specific meaning in signalling.
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Re: Need some help with Wiring Schematics

Unread postby Mike Hodgson » Sun Mar 4, 2018 10:47 am

Yes, the original diagram shows two alternative circuits, both of which define the whole of the logic required to cause that relay coil to energise.
The notes about sectional route release qualify tell you which circuit you would use.

To exspress it like a programming language,

IF sectional-route released required THEN
* circuit one
all of those other relay contacts are in their respective energised positions
ELSE
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Re: Need some help with Wiring Schematics

Unread postby Andrew Waugh » Sun Mar 4, 2018 10:48 am

I would suggest you might find 'Introduction to Railway Signalling' of use. It is available from the IRSE (http://www.irse.org/public/itemsforsale.aspx). The main disadvantage is the price (60 UK pounds for non members).
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Re: Need some help with Wiring Schematics

Unread postby Mike Hodgson » Sun Mar 4, 2018 1:47 pm

Expensive or out of print books do come up second-hand on Amazon or ebay of course.

It may not be obvious that the original diagram is generic in that it shows two alternative circuits, each of which defines the whole of the logic required to cause that relay coil to energise.
The diagram is qualified by those notes about sectional route release - it tells you which of the two circuits you would install. On a generic diagram it doesn't matter which pair of contacts of the relay you use as long as they are of the right type (make or break as required) and it doesn't matter what the supply voltage is as long as it is compatible with the particular relay chosen.

The circuit diagram for an actual box would show additional details such as the supply voltage, the fuse number and which contacts on each relay (for example they might be labelled t1 and t2 or t3 and t4). This information is vital for the technician both to wire it up in the first place and to trace faults subsequently.

As Andrew says it is a logic circuit, so it may help to express the diagram more like a programming language,

IF sectional-route-release-required THEN
* use circuit one which says
IF Fuse not blown AND all of those other relay contacts are in their respective energised positions THEN engerise relay 101WLR

ELSE
* use circuit two
IF Fuse not blown AND a different set of relays are in their energised position AND relay 2DR is de-energised THEN energise relay 101WLR

To understand the logic you need to understand what the other relays do, and the naming convention is very helpful here.
To take one example, in the second circuit 2DR must be de=energised. 2DR is by convention the name given to the relay which, when energised, causes 2 signal to show a green aspect. So its inclusion in this circuit means that 101WLR can only energise if 2 signal is not showing Green (or more strictly, if the relay which causes 2 to show green is not energised).

If you don't have a copy of BS376, this thread should help with what the letters mean : viewtopic.php?f=6&t=5889
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Re: Need some help with Wiring Schematics

Unread postby mreccentric » Sun Mar 4, 2018 4:04 pm

Well, i am understanding it now. But, how are the relay contacts (for ex. in the first circuit) being energised? If different relays are being energised by different coils, then what is the construction of second diagram i have posted (where a set of contacts is been energized by one coil). How does the operator control these relays (if he/she controls the relays 101A, 101B, ....)?
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Re: Need some help with Wiring Schematics

Unread postby Chris Osment » Sun Mar 4, 2018 4:39 pm

mreccentric wrote:Well, i am understanding it now. But, how are the relay contacts (for ex. in the first circuit) being energised? If different relays are being energised by different coils, then what is the construction of second diagram i have posted (where a set of contacts is been energized by one coil). How does the operator control these relays (if he/she controls the relays 101A, 101B, ....)?


The 'simple' answer is that you would need to look at the corresponding diagrams for all the other relays, to see what their individual circuits are. Do not forget also that many relays will not be controlled by 'operators' (ie signalmen), but by various bits of signalling equipment such as circuit-controllers, track-circuits, treadles etc .
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