HISTORY:
Imported from an international research laboratory (by ship!) as the equipment was being disposed of due to the previous establishment upgrading their equipment in the early 2000's. This is yet another very nice item of industrial equipment which I have decided will become an organ donor.
It is the MATSUNAGA (Yokohama Japan) Frequency Converter, intended for laboratory use and providing up to 240V AC at a user adjustable variable frequency. Not only that, the AC voltage output could be varied across a wide range AND the user could set current limiting, so it could alter all three aspects of the AC output wavefrom, frequency, voltage and current limiting. I actually fired this gear up and it was working great but oh dear! What to do with it? Sure you could put up on the workbench but at that sort of weight it needed a lot of space and a good solid workbench. I decided a while back to offer this equipment as a complete unit "elsewhere" online for a while but there was no interest at all so I pondered over what to do with this equipment (to keep or not to keep) but it had a few things going against it.
As a complete unit it was EXTREMELY HEAVY, over 50Kg, which means that my arms are now 30cm longer from lugging this beast around the workshops! ... but more seriously, shipping would have been difficult to ensure safe travel AND very expensive. It also had other minor cosmetic issues because it is not easy moving such a monster around so it suffered scrap marks on various places of the all steel casing.
So, the "donor operation" has begun and here is one of the transformers from this equipment, multiple secondaries at low currents, 100V, 115V or 230V AC source input to the primary.
It is also worthwhile to keep in mind that all of the AC "wound" components (chokes, current transformers, AC step up or down transformers for example) were designed for use across a wide FREQUENCY range, not just 50 ~ 60Hz as the equipment was capable of changing the line output frequency from 40Hz right up to 1Khz
The component manufacturer, Haruna-Denki (Tokyo Japan) began operations in 1981 and remain active in the design & manufacture of generator sets, transformers, high power equipment etc
UNIDENTIFIED - AC Power Transformer
I am absolutely 100% sure this is a HARUNA-DENKI (Japan) product
Made in Japan
Physical: E core laminated
Type #: PT-91023
The transformer ID convention used by the manufacturer is that the secondary ALWAYS has the current rating indicated, the primary only has the source voltage, without a current indication.
Primary AC Voltages: 0V - 100V - 115V & 0V - 100V - 115V
Multiple Secondary AC Voltages:
3x 18V - 0 - 18V @ 200mA each
2x 9V - 0 - 9V @ 200mA each
2x 0 - 5V @ 200mA each
Approximately 31VA total transformer current capability
ALL windings are completely isolated from each other, no multi-taps just centre tapped windings with the exception of the 5V windings which are a single winding each.
There is NO connection between the primary windings and secondaries i.e this is NOT an auto-transformer
Phasing of the multiple windings is not hard to work out so that the various secondaries could be connected in series to create voltages more suitable to the user needs e.g connect two of the 18-0-18 windings in series to provide a 72V AC output @ 200mA which still leaves another 18-0-18 for dual rail supplies and the 5V windings for logic circuits.
Printed on the outer plastic insulation is the clearly marked winding designations and the part # PT-20402A but no manufacturers name. This transformer "build" looks very similar to the VERY LARGE high current transformer HERE so although this AC transformer is not marked with the makers name, I believe it was manufactured by the same company, HARUNA-DENKI (Japan)
Frame has a standard 2x mounting feet arrangement, no mounting screws/bolts supplied
DIMENSIONS:
70mm height x 80mm width x 70mm deep
Base mounting feet extend the width a further 10mm each side, so the total width including the mounting feet is 100mm
Weight: 1.2Kg
COSMETIC CONDITION:
USED (but as new)
NO damage to the laminations or frame
NO damage to the side mounted solder tags, which have been cleaned of previous wiring "dags"
SPECIAL NOTE:
Be very careful and read the solder tag designations correctly, unlike most AC transformers, this one has BOTH the primary source input solder tags (top row) AND some of the secondary solder tags (bottom row) on the same side of the transformer, mixing them up could prove very "interesting"
The frame discolouration that can be seen in the photographs is some sort of varnish finish that the manufacturer applied to the frame.
TESTING:
This is what really matters, how does it perform?
Prior to equipment dismantling, this equipment was functioning just fine (see above) but I wanted to take a closer look at this transformer and the possibilies it offered.
First up, a DC resistance test to make sure all windings are ok (since de-soldering) and isolated between each other and a megger test to frame showed infinity. Definitely each winding is isolated from any other winding.
Let's kick this transformer into life and make some voltage measurements ....
I tested this transformer using my trusty high powered GRUNDIG Variac, in the manner it was designed to be used i.e 115V applied to either primary winding and then wound up the variac and applied 230V to the primary. The output at the secondaries was measured on each winding, all with NO LOAD. All secondaries are fine, reading approximately 10% high without a load i.e 18-0-18 (36V) winding reads 42V open circuit, same sort of situation for the 18V and 5V windings.
NO surprises in operation, looking great!
