dubious soviet tacho generator ДГ-0,5ТВ - Page 1
Forum section: electronics / projects

author: Amper
author_rank: Frequent Contributor
timestamp: September 30, 2019, 08:05:35 pm
content: Hi!I just came back from russia and i brought some NOS aircraft stuff with me, nothing fancy, just some switches, connectors and pots but also two little things i first thought were synchro resolvers by the looks of them. Turns out they are not. I took one apart and inside there is two independent asynchronous machines on the same shaft. One has two windings, the other three, they are built for 30V 400Hz but two phase @ 90° (both machines).According to the datasheet and the units used it appears to me they are some sort of very accurate tacho generator used in analogue computers of the day measuring the speed of the gears inside, while potentiometers do the position work, this way having the derivative for calculating stuff.however i just cant imagne the way they work, i have no schematic, i have no idea which coil has which function and how you can generate a DC output ffrom 400Hz this way.I hope someone can help me out here...This is the datasheet i fund, google translate helps a lot and seems to be accurate enough but it wont give much information, since they assume you already know what you are dealing with.https://eandc.ru/pdf/dvigateli/dg.pdfThis is one taken apart, the rotor consists of two aluminium cylinders, the stators are inserted from opposite sides and the housing has an iron liner for the magnetics to have some path. (sorry for the bad image quality, pic was taken in a rush...)

author: ataradov
author_rank: Super Contributor
timestamp: September 30, 2019, 09:00:38 pm
content: I have not worked with them personally, so may be wrong. Basically you have two coils that need to be supplied two phases of 400 Hz that are 90 degrees apart. Those form a "stator" magnet. Then you have a control voltage that actually drives the rotor.For the tachometer you have another coil that produces the sine or some other waveform that is dependent on the rotor position.They are a nightmare to drive and not particularly accurate.

author: Amper
author_rank: Frequent Contributor
timestamp: September 30, 2019, 09:10:26 pm
content: Mh, It is not a motor, thats for sure, they are used to measure as the output in the datasheet is specified as mV/rpm. Also they are purely asynchronous, the rotor is 100% rotationally symmetric no way of using them for position sensing.

author: ataradov
author_rank: Super Contributor
timestamp: September 30, 2019, 09:15:56 pm
content: It is a motor-generator as suggested by the letter in the name. There is only one winding that's the output. I've seen that parameter in the table. I'm not really sure what that output looks like. It can't be a constant voltage, so that must be an amplitude of somehow modulated signal.

author: Amper
author_rank: Frequent Contributor
timestamp: September 30, 2019, 09:33:11 pm
content: Mh yes, in taht case you are right, though i also found this website:https://auction.violity.com/99118108-dg-0-5ta-dvigatel-tahogenerator-primenyaetsya-v-sistemah-avtomaticheskogo-upr-leniyaand the last sentence of the second block says "For tracking systems with tachometric DC feedback and accurate integrating DC drives, DGs are used containing two-phase controlled asynchronous motors and TGP." which sounds exactly like the machine i have here.The main reason why i think it can not be a motor is because it is commonly used in analogue computers, for example this piece from a mig29 contains similar devices in a slightly different package and a former mechanic / aircraft electrician i know confirmed this. Sadly he did not remember more than this...https://youtu.be/iWrzVnKUCDkThey turn slowly and all parts are mechanically connected through gears.I think the reason for having two asynchronous machines is for them to be counter acting keeping the system from producing torque, as soon as you turn the thing it will generate a voltage on the single sense winding. I will try this tomorrow, first of all i need a 90° power supply.

author: ataradov
author_rank: Super Contributor
timestamp: September 30, 2019, 09:39:28 pm
content: No, it is 100% a motor. There is no doubt about that.I did more reading. Pins 1-3 are a field winding for the motor. Pins 2-5 and 6-4 are control windings for the motor. Depending on the driving mode they can be used in series or parallel.Pins 7-9 are a field winding for the generator (tachometer), and pins 8-10 are the tachometer output.I assume you can try to feed 400 Hz into pins 7-9 and see what you on the pins 8-10 when you manually rotate the shaft.This motor is designed for aviation use basically to drive hands on the dials and other indication equipment. It is very weak to do much more. But it is optimized to have low moment of inertia of the rotor.The 90 degree shift must be between field winding and a control winding. Tachometer/generator may be left unconnected if not used. I think you can just use capacitors to create a 90 degree shift.

author: nuclearcat
author_rank: Unknown
timestamp: September 30, 2019, 10:11:00 pm
content: This is motor-generator pair.Here is translation of forum that i tried to correct.DG-05TB two-phase induction motor generator with a small rotor inertia.It has an motor excitation winding of terminals 1-3 (Uв1)two control windings of terminals 2-5 and 4-6 (which, depending on the control method, can be switched on either in parallel or in series) ( Uy )and two generator windings (excitation winding of the terminal 7-9 generator (Uв2), signal output winding terminal 8-10(Uвых / Uout).Here is circuit diagram present:https://eandc.ru/pdf/dvigateli/dg.pdfDG series engine-generator connection diagram:Uвых - generator output voltage;Uy - motor control voltage;Uв1, Uв2 - excitation voltage of the engine and generatorTechnically it is sort of servo with feedback used in aviation control panels. I attached circuit, but it is ДГ-0.5ТА , which is i guess slightly different.https://www.avsim.su/forum/topic/86469-%D1%82%D0%BE%D0%B6%D0%B5-%D0%BE%D0%B6%D0%B8%D0%B2%D0%BB%D0%B5%D0%BD%D0%B8%D0%B5-%D0%BF%D1%80%D0%B8%D0%B1%D0%BE%D1%80%D0%BE%D0%B2/?page=3Circuit diagram contains lot of aviation specific words, which i am not sure i know english synonyms.

author: Amper
author_rank: Frequent Contributor
timestamp: October 01, 2019, 07:37:24 am
content: Mhm yes, you are both right concerning other versions. Though looking at the schematic you can see that is about the version containing a DC motor. Mine doesn't so this setup does not much sense. Using this motor to drive something is not really logical as in taht case you may just as well use one long motor and not go through the trouble of splitting it up. Both do in fact work as motors using a capacitor as expected but i cant make much sense of it. Also there still is the figure of maximum rpp at 13000min⁻¹ which at 400Hz as a motor this thing can not reach even remotely.

author: Berni
author_rank: Super Contributor
timestamp: October 01, 2019, 08:20:20 am
content: Are you sure this is not a synchro/resolver instead?They are basically transformers with a moving primary that I/Q modulate the AC supply voltage onto its two outputs. They also work in reverse by applying a I/Q signal on its windings the rotor will turn into the according position.Because the principle works both ways means you can connect two of them together, give power to both and then when you turn one of them the other one will follow its motion precisely. This was used quite a lot in the old days to move motion from one place to another over a wire.

author: Amper
author_rank: Frequent Contributor
timestamp: October 01, 2019, 09:29:34 am
content: The reason why i bought them in the first place was because i thought it was a synchro, thats also the reason why i got two of them. But look at the pictures and my first post, it has solid aluminium cylinders as the rotor, no rotating winding, no brushes, no way of absolute position measurement.

author: Amper
author_rank: Frequent Contributor
timestamp: October 01, 2019, 09:46:14 am
content: Oh come on guys, please read previous posts before you reply...EDIT: seems like the related post was deleted...

author: iMo
author_rank: Super Contributor
timestamp: October 01, 2019, 10:49:25 am
content: https://zapadpribor.com/en/dg-05ta/https://zapadpribor.com/en/category/dg/

author: nuclearcat
author_rank: Unknown
timestamp: October 01, 2019, 01:27:15 pm
content: Difference between ТА and ТВ, ТА - heat resistant, ТВ - heat and water resistant. So it should be near same.Here is also some translated description:DG-0.5TV motor-generator is a two-phase unit with a hollow non-magnetic rotor.The phase shift between the supply voltage of the field winding and the control winding of the motor must be done using special circuits that provide an electrical angle of 90 ° regardless of the motor load.The DG-0.5TV mount is flanged.The operating mode is continuous, reversible.The supply voltage of the field windings of the motor and generator is 36 V, the control windings are 30 V.The supply voltage frequency is 400 HzExplanation of the symbol of the DG series:- D - engine; G - generator;- number - maximum motor power, W;- TA - heat resistant; ТВ - heat and moisture resistant; ТЧ - heat and moisture resistant to a supply voltage frequency of 1000 Hz.Here is also book about this motors, but sure it is russian:https://web.archive.org/web/20121101022409/http://www.motor-remont.ru/books/book2/book2p20.htmI will translate relevant part:In automatic control systems, engine generators (DG) are widely used. The engine generator is an assembly consisting of an electric motor and a tachogenerator. Currently, there are ДГ, which include a DC motor and tachogenerator, a two-phase asynchronous controlled motor and a direct current tachogenerator, an asynchronous motor and tachogenerator, a two-phase controlled asynchronous motor and a synchronous tachogenerator.The unit may also include a gearbox. In some cases, DGs are equipped with interchangeable gearboxes with different gear ratios.For accurate calculating devices, tachometric alternating current generators are used, consisting of a ТГА with a linearity of the output characteristic of 0.05 - 0.1% and a residual EMF of 15 - 50 mV, and a two-phase controlled motor.For tracking systems with tachometric DC feedback and accurate integrating DC drives, ДГ are used containing two-phase controlled asynchronous motors and ТГП.For tracking systems of low accuracy, ДГ are produced, consisting of a ТГА and an asynchronous two-phase motor with hollow rotors. The linearity of the output characteristic of such ДГ is about 1%, the residual EMF is 100-200 mV.-----18.4.2. ДГ series motor generators<< this was translated before >>The supply voltage of the motor and generator excitation windings is 36 V, the control windings are 30 V. The supply voltage frequency is 400 Hz, ДГ-Т4 type DG is 1000 Hz.The diagram of the connecting of DG series motor generators is shown in Fig. 18.16, the main technical data are in the table. 18.18, overall and installation dimensions and mass - in table. 18.19 and in fig. 18.17.

author: 001
author_rank: Super Contributor
timestamp: October 01, 2019, 01:32:47 pm
content: try to ask it at russian aviaforums