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Author Topic: EVS 2KVA AC mains voltage regulator with thyristor ( inside view ) by STB Greece  (Read 1870 times)

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Offline Kiriakos GR

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This is a 2.5 KVA AC mains voltage regulator with thyristor, and is a custom build, designed to serve as protection of sensitive medical equipment.

STB brand is probably the naming of a small Greek industry or the logo of a maker which has skills in assembling such devices.

This AC mains voltage regulator belongs now to me and I received it as gift, it job is now handled by several  Battery Backups/UPS Units.


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Offline giorgos

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A complex construction, that remids past years when Greek industry was more active than nowdays...

Offline Kiriakos GR

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When I got this item this came with zero documentation, but today I did test it by adding as input my new Variac Transformer.

Now I am aware that this stabilizer it does precision work at delivering an output of 230V with input voltage of 190V up to 250V.  8)
Internal circuit this acts as constant active inverter and it does an annoying buzzing sound all times.

This stabilizer it does a good job at stabilizing, it is clean of harmonics noise, but it does that by it self consuming significant power even with out load at all.

Worst consumption condition this is at 190V input and consumption get lower at higher volts.
When input this is 230V and output 230V at that moment there is a minimum of 575 VA of consumption with out load but with Power Factor 0.04 actual Watts are approximately 28W Power meter TS-836A
 
Here are values of recorded consumption according to input voltage: (Variac Panel meters)
6A  ---->  190V AC Input
2.8A  ----> 225V
2.5A  ----> 230V
2.1A  ----> 235V 
1.6A  ----> 240
1.2A  ----> 245
0.5A  ----> 250

In the positive side of things and what makes me extremely happy, this is that specific stabilizer it handles very well load conditions.
Voltage stability at 230V this is superb.  ;)
295W lamps load: 230V, 1.27A, PF 1.0 (at the side of the output). 
Total load at the Mains input this is 326W (prior the stabilizer, and at Variac output).
What is interesting this is Power Factor between Variac and stabilizer (between two transformers), this measured 0.43 PF
 
IEC standards require the nominal voltage (230v) +/- 1 % and frequency (50Hz) +/- 1% with a Crest Factor between 1.34 - 1.49 and a Total Harmonic Content (first 13 harmonics) under 2%.
Therefore this stabilizer it seems excellent for testing of power meters and of power quality analyzers,  especial when voltage stability after several confirmation measurements this is at 229.5V ~ 230.5 V   8)

Programmable ACV sources today comes for a price of 2500 ~ 3000 or more Euros.
My stabilizer this is fixed at 230V but either way, it is fixed exactly were it must be so this equipment to have great value for me and ITTSB Blog.   
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