what are these components?

[mike-gr]

Hello everyone!
I want to ask the old guys in here if they know what are these components on the photos no 2 & 3?
These things are part of the electrical system of an old hydraulic "clicker" press. It's used to cut leather,paper etc. The machine is probably from the 70's and there is no tag on it so i don't know any infos!
It's working ok but i am thinking to either change the 3 phase electric motor with a new single phase motor or make this one single phase! My problems are these 2 components! I don't know how they will be affected from this change! The machine have 2 handles with one button each. To make the head move downwards you must press both buttons (i guess as a security measure so that you always have both hands safe). The buttons are connected with this component. I know there is a big electromagnet in the head (next to the buttons) that moves a lever that actuates the downwards move of the head.
I already asked the company but they don't have any pdf for this machine anymore!

 

[pc1966]

The 2nd one looks like a transformer to me, but it could be a choke (inductor for smoothing DC supplies) if it only has two wires.

The 3nd one (red finned thing) is probable a rectifier, and probable a selenium one. In the days before reliable germanium or silicon diodes for low voltage (AVO meter, etc) you would see copper oxide ones, for higher voltage selenium. The selenium ones smell awful if they overheat!

Hard to tell from just the photos.

 

[westward10]

The second picture is a bridge rectifier used to convert ac to dc the other is a transformer.

 

[mike-gr]

I guess they don't require 3phase current!

 

[pc1966]

No, they would be fed of one of the phases is my guess. You would really need to try and draw out the schematic before touching anything so you have a better feel for what is in there.

And lots of photos! Always handy to look back if you discover something is wrong.

 

[westward10]

Hard to say and assuming that is an isolating transformer it may have a 400v primary, does the existing supply to it incorporate a neutral conductor.

 

[mike-gr]

I'll take a few more photos and i will be back!

 

[DPG]

Haven't seen a selenium rectifier for a while. Lovely. Just needs a mains dropper resistor as well (barreter?)

 

[mike-gr]

ok! Here we are again! I will try to describe as best as i can!
The white cable (number 1 & 2) comes directly from the switch.
The next 4 cables (3,4,5,6) goes directly to the buttons on the head of the machine, the electromagnet i mentioned before.
The number 7 & 8 goes to the silver thing (transformer i think) in the picture "atom press2.jpg"
From this little silver thing then comes 2 cables the No 12 & 16.
The cables No 13 , 14 , 15 are connected to the red finned thing.
The black round thing on the top right of the picture was probably a fuse but now in not connected with anything. To better understand the pictures "atom press2.jpg" and "atom press3.jpg" it's the same part of the machine, one from inside (atom press2.jpg) and from outside (atom press3.jpg)

 

[westward10]

That black thing is not a fuse it is a voltage selector.

 

[mike-gr]

That black thing is not a fuse it is a voltage selector.

Anyway it's not connected with something!

 

[westward10]

Anyway it's not connected with something!

The connections will be below it, not clear of it's purpose.

 

[DPG]

Anyway it's not connected with something!

Maybe it's been bypassed at some point.

 

[mike-gr]

Maybe it's been bypassed at some point.

i think so!

 

[snowhead]

You can see the back of the voltage selector above the transformer, Atom press 2, picture.
Nothing connected, was probably for the original transformer now replaced with the silver one.

 

[freddo]

Any manufacturers information is probably only going to be of limited help as most of the components shown appear to have be (sloppily) installed at some point in the past and it is likely none of them are original.

As you have already worked out the circuit appears to be:
Power from the mains switch feeds the silver transformer primary, the transformer secondary is switched by the pair of operators buttons which sends extra low voltage AC to the red bridge rectifier, the DC output from the rectifier operates the solenoid actuator to trigger the press to operate.

The voltage selector was probably for selecting the input voltage to a previously removed transformer with multiple primary voltage tappings. The selector knob might also house a small fuse.

 

[mike-gr]

You can see the back of the voltage selector above the transformer, Atom press 2, picture.
Nothing connected, was probably for the original transformer now replaced with the silver one.

That's right!
Now my question? If i change the input current (cable 1&2) to single phase 220V will these components work?

 

[westward10]

You need to know the primary voltage of the transformer.

 

[mike-gr]

You need to know the primary voltage of the transformer.

You mean i have to measure the current voltage at the white cable No1 & 2?

 

[Lucien Nunes]

Better to either read it off the transformer or see how the supply to is is configured.

If the machine does not have a neutral connection, the transformer must be 400V. If you are lucky, it will have an internal tapping selector to alter to 230V, under one of the silver end covers. If the machine has a neutral connection, and the transformer is connected between that and one phase, it is 230V and will work with the single-phase supply without any alteration.

If the transformer is 400V only, you have two choices. Find out what its secondary (output) voltage is and replace it with an equivalent with a 230V primary, or, rather clumsily, step the 230V up to 400V feed this one.

 

[mike-gr]

A better photo of the trasformer!

 

[pc1966]

If there are likely to be big issues in converting from 3-phase to single you might want to look at getting a static converter to generate 3-phase from your single phase supply.

 

[mike-gr]

If there are likely to be big issues in converting from 3-phase to single you might want to look at getting a static converter to generate 3-phase from your single phase supply.

That's the other way around! I have to check this too!

 

[Lucien Nunes]

It's worth mentioning that a 230V transformer to do this job will not be massively expensive, but it will be important to discover the output voltage of the present one. If you are equipped to work safely on live equipment you could measure the AC voltage between terminals 1 & 2 which is the transformer supply. If it is 400V and you need to replace the transformer, then measure between terminal 12 and wire 16 with the buttons pressed, which the secondary voltage and is more likely to be 24V or similar. Then, disconnect the brown wire from terminal 6, connect your meter on AC amps between the terminal and the wire, and press the buttons to complete the circuit and confirm the secondary load current.

 

[mike-gr]

It's worth mentioning that a 230V transformer to do this job will not be massively expensive, but it will be important to discover the output voltage of the present one. If you are equipped to work safely on live equipment you could measure the AC voltage between terminals 1 & 2 which is the transformer supply. If it is 400V and you need to replace the transformer, then measure between terminal 12 and wire 16 with the buttons pressed, which the secondary voltage and is more likely to be 24V or similar. Then, disconnect the brown wire from terminal 6, connect your meter on AC amps between the terminal and the wire, and press the buttons to complete the circuit and confirm the secondary load current.

Now i am beginning to have an idea of what is happening! I will try to do the measurement with an electrician friend!

 

[mike-gr]

Just a thought! What if i use a power supply to transform and rectify the current and feed this to the buttons?

 

[Lucien Nunes]

That is possible too, but depending on the voltage a relay might be needed because the buttons (which switch AC at the moment) might not be suitable to switch the DC. (they are on the AC input side of the rectifier for good reason). In any case, either the existing rectifier or a new diode must be connected as a discharge diode around the magnet coil. Without that, the inductive voltage spike would soon destroy the switch/relay and even the coil insulation. The existing rectifier provides this function in addition to converting AC to DC.

 

[pc1966]

I'm wondering what it is for, DC injection braking perhaps?

In that case going from 400V delta-connection to 230V Y-connection might not be such a big deal. Going the other way would be!

 

[westward10]

Not sure where the term clicker derives from but I have worked in many of the Northamptonshire shoe factories where shoes are still hand made, John Lobb being an elite brand across the world. Fascinating places still using traditional methods and they all have clicker rooms where the leather is cut and graded. People who work these rooms are known as "clickers".

 

[mike-gr]

one more photo of the rectifier. Italian made!
I took some measurements
The voltage on the primary coil of the transformer is 400v.
The output of the transformer is 45v and when i press the buttons the current is 3Amp.
The magnet receives 40.5v from the rectifier!!! (is the rectifier cause this drop in the voltage?)
Inspecting the whole thing i understand how it's working!
The AC after the tranformer passes through the rectifier with the 2 buttons interfering so that only when I press them the 45v DC goes to the magnet and causes the hydraulic piston works!

 

[Lucien Nunes]

The 40.5V DC that you measured might not be strictly accurate because of the waveform. The rectifier output voltage is DC pulsating at 100Hz, however the current through the magnet is probably fairly smooth DC because of its inductance. When the voltage from the transformer secondary drops too zero on each half-cycle of the AC waveform, the magnet current continues 'flywheeling' through the rectifier.

Selenium rectifiers drop approximately 1-2V per plate under load. Unlike silicon diodes where a single diode junction can be made to withstand >1000V in reverse, each selenium junction can only withstand a few tens of volts. To make a rectifier with higher PIV, multiple plates must be stacked in series, each adding to the voltage drop. Your rectifier appears to have two plates per diode, therefore as two diodes are always in series with the load, a forward drop of 4-6V would be reasonable. Note that there is an extra diode at the bottom not in use.

 

[mike-gr]

So i need to check the electric motor now if it's possible to make it run under single phase or i have to change it with a new one. I will also need to change the transformer with another one for 230/45v.
If i use the same rectifier will that be a problem?

 

[westward10]

Transformer will be a straight swap you just need the correct va, rectification can be left in place.

 

[Lucien Nunes]

Something like this might suit:
200VA 230/400 - 2x24V isolating transformer

 

[mike-gr]

Something like this might suit:
200VA 230/400 - 2x24V isolating transformer

This one have an output of only 24v! The one the machine have is 40v!

 

[DPG]

This one have an output of only 24v! The one the machine have is 40v!

I'm guessing Lucien intends you to connect the secondaries in series.

 

[westward10]

Output is 2×24v and you can normally connect for 24v parallel or 48v series.

 

[Lucien Nunes]

Indeed, and with a +15V tap on the primary, you connect the 245V primary to 230V and the 24+24V secondaries in series give you 45V as per the existing one.