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HTN Family

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Toroidal three-phase Variacs

HTN Family

General Info
Metrel Variacs are made of high quality parts and have followed advanced technological studies.
The cooling surfaces have been improved and increased, to avoid extra heating at the brush contact point with with the track, even under continuous and heavy use.
The correct use is thus assured for longer periods and without performance losses.
The Variacs conform to the standards  VDE 0552 and international standards IEC 60989.

The Variacs are designed to be rested horizontally on a bench.
The single-phase models come with a cable, bipolar led switch, output connection and protection fuse. 
The three-phase models are available with a cable and bushing output.
Each model has a regulating knob and indication panel of the output power in percentage.

Ambient Temperature 
The Variacs are designed to assure a correct function up to 40 C.  Higher temperatures need a forced cooling system or a reduction of the Variac's services by 15% for every extra 10 C (ex.: a 20 A Variac must be reduced to 17 A max).

No particular maintenance is needed, when the Variac is used in normal conditions.  Periodical cleaning is required by eliminating dust from the contacts track, along with a check up of the brush, controlling that it is intact and long enough to allow a correct pressure of the spring .
In dirty and salty surroundings, it is advisable to clean the sampling track with fine sandpaper or a deoxidizer.
If the brush contact is no longer safe and must be substituted, please do the following:
- with a welder, unweld the the copper cord which gives current to the brush. Loosen the slider at the output connector and when the used brush comes off, insert a new one and reconnect it.
- tighten and adjust the slider two to three mm. from the sampling track surface.

Connections and Protections
The input power must not exceed 6% of the nominal, to avoid possible coil over heating.
The output circuit, conform to the standards VDE 0552-5.69, must be protected against voltage overloading and short circuiting with fuses and thermal protections.
The primary circuit must be protected with a delayed fuse with correct values for each output.

Technical features

Input Power 400 V
Output Power from 0 to 400 V -
Art. No. In A Output power Weight (kg) Model Fig.
HTN450/8 8 6240 28.6 3/M200 20
HTN450/10 10 7800 35.2 3/M250
HTN450/15 15 11700 51.7 3/M300 21
HTN450/20 20 15600 54.8 3/M400
HTN450/30* 30 - - 3/M500
* under study


Model a b h l Fig.
3/M200 240 285 380 420 20
3/M250 240 285 380 420
3/M300 285 315 480 520 21
3/M400 318 348 480 520
3/M500 357 387 540 590

Technical sheet download in PDF

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