Talk:Relay

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[edit] Sugestion for External Link

To whoever is "managing" this page, may I suggest an external link to the "Heath Robinson Rube Goldberg (HRRG) Mixed Technology Computer" project at http://www.diycalculator.com/sp-hrrgcomp.shtml. The idea is to create a computer out of a mixture of implementation technologies, including relays, vacuum tubes, transistors, simple integrated circuits, pneumatic logic, magnetic logic, and so forth.

Just an FYI. No need to ask to add something. The person who is "managing" this page is you (well everyone that is). Good link idea so I am adding it. 69.72.2.72 01:48, 17 March 2007 (UTC)

[edit] Contact Rating

There seem to be two ratings for contact current: Carry current and Switching current. I think it would be useful to define these terms.

-JKoether


== Track Circuit Relay

(Railway) ==

[edit] Italy

hello

I have a problem related to a special tipe of relay, used in Italian railway, called "disk ralay".

This tipe of relay has two solenoid, with two SINUSOIDAL currents, I' and I", and the force on a alluminium disk depend on the current intensity and the phase of two currents. The force is proportional on this formula: C= K*I'*I"*sen(a) (*), where a is the angle of phase between sinusoidal current I' and I".

The couple C must be more than a particolary minimum value: if this is not, the relay go "down" , and this is an alarm. This tipe of relay is used to misure the returned current from the field in a circuit that control the free/not free state on a railway track: current I' is local, current I" is from the field.

Due to the presence of the angle a in the couple formula, the retourned current must have a phase angle strictly on a specific range, around 90°.

Well, this description is the antefact, the answer that I don't know is another: If I apply another type of current to the disk relay, for example, not sinusoidal, but for example rectangular pulses, how can I modelized the value of the force C on the disk?

With the Fourier transformer, I can divide the pulses on the disk with more sinusoidal pulse, with frequencies f, 2f, 3f, etc. .

I can say that the force C must be C= C(f) + C(2f)+ C(3f)... where each C(f) is the part of the original pulse diveded with the Fourier Transformer, with the formula (*) value for every frequency, with angle a(f), a(2f), a(3f).. ?

This answer could be important to understand if the pulse is not sinusoidal how can I decide the couple.

If everyone knows ideas, could be sended to l.carlini@rfi.it

Thanks

[edit] General

The description of the Italian railway relay above sounds like an AC Vane Relay.

These relays are used on electrified railways to detect the presence of trains and operated the signals. Because the power of the traction (1 MW) is so much greater than the power of the track circuit ( 1W ), special precautions must be taken to prevent the traction current swamping the track circuit current leading to a false green. In the AC Vane relay, the track circuit current at the relay has to be in the right phase compared to a reference current, and this provides the necessary imunity.

AC Vane relays are however fairly insensitive, and require undesirable insulared blockjoints and are being replaced by more modern electronic relays, some of which are jointless.

[edit] SPDT, DPDT, ETC

Information should be added to the "Relay" article defining the meaning of "poles" and "throws" such as SPDT and DPDT. I would attempt to add it myself but I am fuzzy on it myself.

Added the information. Please see if its ok. Rohitbd 12:59, 1 March 2006 (UTC)

The switching information gets lost in the "Types of relay" section and ends up looking like it is a continuation of the types. Should it be broken out into another heading, or just better distinguished and stay here? Regardless, I think it needs something to keep it from being lost in the clutter. --Stangbat 18:33, 8 December 2006 (UTC)

[edit] Irrelvant Entry

I removed "reed switch" but left reed relay. A reed switch that can detect the presence of a magnet is a sensor Commonly used in security systems to tell if a window has been opened. I also removed "vibrator". It doesn't relay a signal, it generates one. Once common in mobile radios. Bell was also removed.Seán 07:54, 12 March 2006 (UTC)

Relays may also be operated by heat where a coil heats a bi-metal strip to open contacts, or where a solder pot melts, releasing a spring to operate contacts. Such heat-activated relays are commonly used for motor circuit protection.

THis does not fit with headline defn and is therofore NOT a relay. How can we handle this one without deleting it I wonder. any suggestions??? Light current 22:48, 4 August 2005 (UTC)

Move it to sensor or switch, or both? --Heron 21:30, 5 August 2005 (UTC)
I have joined it with contactor. Bi-metallic relays were once common for time-delay circuits - another section. Meggar 02:03, 2005 August 6 (UTC)
Are you talking about a klixon? 19:04, 2005 October 25 (UTC)
I think Meggar is referring to "overloads". In any event, if it's bi-metallic, it's temperature sensitive and not time sensitive which is what's needed for a time delay.Seán 23:46, 5 March 2006 (UTC)
Bi-metallic time-delay relays had a heater that warmed up the strip over some time, after which it would open or close. They were common items once. The "overloads" also involve time to match the heating rate of the motor that they protect. Meggar 00:42, 6 March 2006 (UTC)
I've never seen one that I can think of. Could you help with an example? All of the overloads I've ever used required me to look at the data plate of the motor and find the FLA (full load amperage) and select the proper heater that will trip at that current. Electric motors have a short period during startup where they draw "inrush current" which can be ten times their rated current. The overloads are designed to ignore this. Seán 01:20, 6 March 2006 (UTC)

My apologies - Meggar pointed out an example I hadn't seen since the sixties. I had forgotten thermal time delay Seán 02:02, 6 March 2006 (UTC)


[edit] Circuit symbol

The article does not contain the circuit or schematic symbol of a relay. Rohitbd 12:20, 1 March 2006 (UTC)

I will try to find one or draw it myself. Be patient, I just started. I have yet to play with the drawing utility Seán 23:46, 5 March 2006 (UTC)

Added the image showing circuit symbols of relays. Please check if it is ok. Rohitbd 12:59, 1 March 2006 (UTC)

It does indeed show the relationship of SPDT as compared to DPDT, however, a relay is usually depicted in the relaxed position. Seán 23:46, 5 March 2006 (UTC)
Hmm...although I am not sure what a "relaxed position" means...perhaps you could make that change...? If it is any help, I have used MS-Paintbrush to create the image. Rohitbd 11:20, 6 March 2006 (UTC)
The relaxed position is where the contacts would be if the coil is not enegized. In the case of DPDT (double pole - double throw) the NC (normally closed) contacts would be closed. The contacts in the picture are shown midway between energized and relaxed. In a high current application this would cause a lot of arcing. I just printed out the page on how to upload graphic files. Seán 00:20, 8 March 2006 (UTC)
Changed the image to reflect the relaxed position. Please see if it is ok. Also, please sign your posts with ~~~~. Rohitbd 19:38, 7 March 2006 (UTC)
There is a drawing somewhere on the relay itself. [[1]] Seán 00:30, 8 March 2006 (UTC)
Notice how terminal 5 (common) is shown connected to terminal 1? This is the circuit when the coil is de-energized or relaxed. When the coil is energized or activated, terminal 5 will be connected to terminal 3. The coil is drawn as a zig-zag line. The symbol is similar to the symbol for a resistor. The drawing is simply trying to show a fixed load. The current draw of the coil is consistant no matter what current the contacts are carrying. Also notice how the coil is shown as a separate circuit? This is electrical isolation.Seán 03:01, 8 March 2006 (UTC)

[edit] Time Delay

Time delay is mentioned at least twice is this article. There are time delay devices attached to relays. There is "delay on" where the coil is energized and some mechanism holds the contacts completely open for a set time. After the set time, the mechanism lets go of the contacts and the magnetic force of the coil quickly takes the contacts from all the way open to all the way closed. In the delay off style, the coil is relaxed and some mechanism holds the contacts all the way closed for a set time. After the set time, the mechanism lets go of the contacts and the force of the spring carries the contacts from all the way closed to all the way open quickly. There are several different mechanisms. There are clocks and electric motors and dashpots which are small pistons that release fluid slowly. All of them incorporate a trigger that releases the contacts quickly. All of them are time sensitive not temperature sensitive. The copper disc is used on the solenoid/armature of an AC coil. AC current would relax its hold on the contacts 120 times a second as the alternating current passed through zero. The copper disk prevents that. Seán 00:58, 6 March 2006 (UTC)

Thermal time-delay relay [2]
Yes the copper disk used on all AC relay coils to prevent buzzing, fits around part of the coil to delay the phase of the field and prevent zero flux trouble. There is also a DC dropout time delay done with a copper disk around the entire coil as described in the article. Meggar 01:13, 6 March 2006 (UTC)

[edit] Latching relays

Someone needs to do a better job of describing latching relays, especially the simple latching relays that factory machines use (with green start buttons that are recessed and red stop buttons that have to be pulled out to allow restart). Anthony717 23:10, 28 April 2006 (UTC)

What does it mean by "two darned relaxed states"?--24.57.106.78 (talk) 00:21, 7 December 2007 (UTC)

[edit] Images

Not that you need it, but here's another image. Fit it in if you want. — Omegatron 06:54, 10 June 2006 (UTC)

[edit] Unusual relay

Is there any major application for an unusual thermal (not bimetallic) relay with these properties: High current/low voltage (output) huge operating temperature range (0K - 700K or so; theoretically as high as 2500K with the right materials) operates better the smaller it is; power used is proportional to the cube of its size. Theoretically would use less power than a transistor if you made it with transistor-scale dimensions. As a macroscale device (millimeters across) uses milliwatts of power to switch and stay switched. requires precision manufacturing and/or assembly to .03% of one dimension on a relative scale between two parts. They can both be a little big, or both be a little small, but in the same proportion to .03% of that dimension.Cuberoot31 21:57, 26 October 2006 (UTC)

[edit] Transatlantic cable

Can this entry be clarified? Does it really even belong here? From reading the entry on the Transatlantic Cable page I can figure out where the author was headed, but without further explanation, this entry really makes no sense. --Stangbat 20:23, 27 October 2006 (UTC)

You're right, thank you. This very interesting receiver is basically a galvanometer; not a relay at all. I have moved the relevant portion to the speed section of the atlantic cable article (without leaving a link) and deleted portions that would be redundant there.
This article also has an excessively long lead. The material about contact types would fit better in one of the sections.
Jim.henderson 18:03, 8 November 2006 (UTC)

Anybody help me with some info on timing relays? like the basics , would be helpfull. thanks. —Preceding unsigned comment added by 217.34.40.93 (talk • contribs)

[edit] Noise

You say

Contactor relays can be extremely loud to operate, making them unfit for use where noise is a chief concern.

but you don't say if you are referring to the constant buzzing, or the kerchunk upon closing and opening of the circuit. Also see Talk:Contactor. Jidanni (talk) 01:19, 28 February 2008 (UTC)