What is this, and what does it do?

[RF Lighting]

I was working on a TP machine in a commercial printers today, and in the control panel I was greeted by a strange component.

It appears to be some sort of solenoid, and where the two blue wires connect to it there is mercury.

The solonoid is pulled up (breaking the contact) when the motor is switched on.

It is quite an old machine, but not too old for contactors.

Why would this be fitted instead of a contactor or relay?

This is the whole control pannel

 

[ricicle]

Could be some kind of failsafe device - something that needs energising in an emergency (eg brake).The mercury will never fail to conduct and will not suffer pitting as a normal contact eventually would???

Definately one for EN60204 and the HSE department.Careful if you touch it, we don't want you going mad(der)!!!!

 

[securespark]

Looks like some kind of coil - like the solenoids Xpelair used to use in the GA6 wall fan to open the shutters??

 

[JohnD]

Mercury is sometimes used in "tilt" switches that make contact when in a particular orientation. Is it fixed to anything that could move, or fall over?


OOI, is that a glass component sticking out of the top, with a clamp round it?

 

[RF Lighting]

The control panel is solidly fixed to the machine, which is a big cast iron thing. Easily over a 1000kg

The component is a glass tube with like two bulbs at the bottom where the blue wires are attached. The bit with all the writing on appears to be a coil which when energised pulls some sort of actuator (inside the glass tube) upwards out of the mercury.

 

[bernardgreen]

The control panel is solidly fixed to the machine, which is a big cast iron thing. Easily over a 1000kg

The component is a glass tube with like two bulbs at the bottom where the blue wires are attached. The bit with all the writing on appears to be a coil which when energised pulls some sort of actuator (inside the glass tube) upwards out of the mercury.

Any circuit diagrams ?

The simple answer is it is a relay with mercury wetted contacts to ensure that the contacts always close when the coil is de-energised. This could be for a dynamic brake on a motor ( shorting the motor out ).

But the coil appears to be wired to a variable control which suggests a threshold can be set for something. Current flowing in mercury in a magnetic field will try to move at right angles to the current and magnetic field. ( how motors work ). If the current is too high then the mercury "snaps" and break the current, the "breaking" current depends on the strength of the the magnetic field so this could be a form of self re-setting MCB where the trip current is set by the current is in the coil.

It may be used in the speed limiting of the motor.


Bernard
Sharnbrook

 

[RF Lighting]

Ahhhhhhhh

Lightbulb moment!!

So it might be that the actuator is infact insulated, and displacing the mercury and breaking the circuit when the coil is de-energised, rather that as first though, with the actuator making the circuit.

I am not sure if there is a brake on the motor or not. I was repairing a fault on a heater part of the machine, so didn't really get involved with the motor side. I was just curious.

Sorry there are no circuit diagrams, and judging by the the panel wiring colours I am not sure it is a British machine. Red is used as earth, black as L1,L2,L3 and grey/white as neutral.

 

[bernardgreen]

Ahhhhhhhh

Lightbulb moment!!

So it might be that the actuator is infact insulated, and displacing the mercury and breaking the circuit when the coil is de-energised, rather that as first though, with the actuator making the circuit.

I am not sure if there is a brake on the motor or not. I was repairing a fault on a heater part of the machine, so didn't really get involved with the motor side. I was just curious.

Sorry there are no circuit diagrams, and judging by the the panel wiring colours I am not sure it is a British machine. Red is used as earth, black as L1,L2,L3 and grey/white as neutral.

It is almost certainly German (or Germanic ) Red was earth in the 1940's Germany ( equipment bought back by soldiers and wired British standards wa lethal with red earth going to live ).

The mercury bottle is German,

As for "light bulbs" have a look at

http://www.hts-homepage.de/Klingerpark/Klinger5.html Mercury arc 3 phase to DC rectifier. ( and early sun tan machine )

 

[RF Lighting]

Another clue is the fuse panel and schuko socket round the other side

BTW what a frighteningly fantastic link

 

[ricicle]

Good chance its German or Scandanavian with those TDZ fuses.We have those in some of our machines at work.

 

[breezer]

I remeber seeing one of the rectifiers in the science museum.

oh, and if any one wants to read wht it actualy says click me

I was also thinking doesnt the top part look like gort

 

[RF Lighting]

Foreign buttons too.

Think this is an inch button

 

[DESL]

Ah touch of nolstalgia here I remember the mercury arc rectifiers at college on the old heavy duty generators.

I think some of them had come from British Rail used on the first electric trains which use Ward Leonard speed control - I guess there's no one old enough to remember that.

 

[ricicle]

I think some of them had come from British Rail used on the first electric trains which use Ward Leonard speed control - I guess there's no one old enough to remember that.

Ward Leonard - Motor/Generator sets.One of my favourite subjects (Motor control)

 

[bernardgreen]

Ah touch of nolstalgia here I remember the mercury arc rectifiers at college on the old heavy duty generators.

I think some of them had come from British Rail used on the first electric trains which use Ward Leonard speed control - I guess there's no one old enough to remember that.

Yes there are people that old and still active. I call them youngsters......