Reduce the size of switchgear designs and increase safety

ARLINGTON HEIGHTS, ILLINOIS, USA, Monday, June 24, 2013: Hill Tech Sales, a leader in Components for Electrical Power Conversion today posted information on using true Full-range fuses to reduce the size of switchgear.

In the past, Full-range fuses used an inappropriate element design where they “age” prematurely because they operate in the fast overcurrent range. This ageing is the changing element’s characteristics because of the increased power loss during operation.

Correctly designed Full-range fuses will interrupt any value of current from short-circuit to overload interruption. They have all the characteristics of back-up fuses plus the further ability for protection in the overload range. Distribution transformer circuits should use Full-range fuses where there may not be protection on the secondary side of the transformer, and the primary fuse is needed to clear a secondary system fault.

Full-Range fuse other construction concept

Back-up & General Purpose fuse

Typical construction for Back-up & General Purpose fuses

 

 

 

 

 

 

 

 

 

 

Our Full-range fuses are designed using a two zone design concept; each zone has a different element design which lowers power losses and temperature rise leading to reliable operation in the overload range.

Full-Range fuse NEW concept

A true Full-range fuse uses a dual zone construction

Other Full-range fuse do not use a dual zone construction

 

 

 

 

 

 

 

 

 

 

New design concept for Full-range fuses:
Two Zone concept, back-up zone, overload zone (Thermal Zone)
Special melting element material for parallel melting element design

Back-up zone
Back-up zone consists of upto 15 individual silver melting elements wound onto a star-shaped carrier imbedded in quartz sand.

Overload zone (Thermal Zone)
The elements in this zone are notched, which reduces the element cross section generating power loss and creating heat. In order to minimize the effects of this heat, two things are done. First, the heat is confined to a thermal separated from other parts of the fuse by a thermal barrier. Secondly, the melting elements are made of a special alloy differentiating it from silver (melting point 960°C) which is typically used.

Note the two different windings in this Full-range fuse

Full-range fuse dual zone method

 

 

 

 

 

 

 

Melting element materials has three important properties:

  1. Low melting point ~ 600°C.
  2. Enhanced heat absorption by the decay of metal-oxide components in the arcing process. Metal oxides are created by internal oxidation of the alloy just before reaching the melting temperature.
  3. Increased recovery voltage. The AC voltage arc is immediately absorbed after current zero making re-ignition very high. These fault arcs are extinguished much faster when made of this alloy as compared to elements of pure silver.

The two zones are placed in series for good short-circuit and overload protection.

Full-range fuses protect like two fuses, Back-up & General-Purpose.

Why Full-Range fuse is better than Back-up or GP

Why Full-Range fuse is better than Back-up or GP

 

 

 

 

 

 

 

 

 

 

 Full-range fuses protect the transformer by:

  1. Meeting transformer inrush current points.
  2. Have a rated current sufficiently above the transformer rated current in order to allow for admissible overloads.
  3. Provide best possible protection during overload caused by winding short circuits.
  4. Discriminative currents over the complete interrupting range.

Increasing Switchgear safety

Switchgear safety can be increased by using Full-range fuses on the high voltage side of the transformer because other methods only protect against:

  • Non coordinated fuses on the low voltage side of the transformer
  • Short circuits in the transformer winding, ie transformer insulation failures
  • Earth faults in the area around the transformer bushings

The danger of this method is that admissible peak transformer currents are exceeded when the cables are loaded with their maximum, and transformer life-reducing excessive loads are only noticed after years.

Also, back-up fuses used on the primary side of the transformer do not protect in an overload range situation where the insulation is in the process of failing. A slow steady current rise can occur when cracking insulation causes more and more windings to short-circuit. This increase in current occurs in the small overcurrent range of the transformer.

Full-range fuses will effectively protect transformers against overloads caused either by the load or winding short-circuit. These fuses can be used as redundant protection so that even after failure of all other protective devices on the high and low voltage side, it offers a last means of safety before catastrophic damage occurs to your installation, buildings and environment.

Consider Full-range fuses for applications with long cable runs and/or high transformer impedance and Switchgear without 3-phase disconnecting device.

Reduced size and cost of switchgear by Full-range fuse

Back-up fuses need to be de-rated in transformer applications. For a 100A application a 125A back-up fuse would typically be used. With Full-range fuses, there is no de-rating of the fuse value, so a 100A is appropriate for a 100A application.

Protecting distribution transformers with full-range fuses

HV fuse should be located here to protect transformer

Schematic showing HV Full-range fuse location in order to protection transformer

 

 

 

 

 

 

 

 

 

 

 

Ratings available:

  •  6/12 kV:              6.3 A – 100 A
  • 10/24 kV:             (6.3 A) – 50 A

 

 Applications: 

  • Power centers
  • Power transformer protection
  • Load interrupters
  • Feeder circuit protection
  • Mine rectifiers

For more questions on this article contact:

Andrew Hill
Hill Technical Sales
216 West Campus Drive
Arlington Heights, IL 60004
Tel: +1- 847-255-4400 ext 12 Fax: +1-847-255-0192

You may also visit: http://www.hilltech.com/

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Innovative welding technology reduces cost on liquid cooled Cold Plates – FSW

ARLINGTON HEIGHTS, ILLINOIS, USA, Tuesday, March 19, 2013: Hill Tech Sales, a leader in Components for Thermal Management and Electrical Power Conversion today posted information on friction stir welding in a cold plate construction.

Recently the only way to make certain configurations of high thermally efficient aluminum cold plates was by brazing. This is where a base, fins/tubulators and cover plate are brazed together to form one complete assembly.

Most designers would choose to avoid brazing if possible because of the inherent cost and issues that arise.

  • Annealing
  • Wasted material
  • Increased machining costs
  • Internal debris
  • Additional QA and testing

Annealing – When brazing is done the material is converted from its original temper, the annealing process re-creates the original hardness.

Wasted material comes about from more material being used to compensate for the distortion (warping/twisting) that occurs in brazing and post brazing annealing process. This allows the part to be machined to the original tolerances, with details and flatness required.

Increased machining costs occur because of the ability to consistently heat-treat a part. It is very difficult to accurately anneal a brazed part to a consistent hardness; the larger the part, the more difficult it becomes. This results in the machining being done at a much lower speed (increasing machine time). Why does this happen? When you run a part with inconsistent hardness through the machining center, if it is cutting through some material with a given hardness at a certain speed, and then all of a sudden hits a soft section, it will move through that material in a much more rapid and unpredictable manner, making it difficult to control machining accuracies and flatness.

Internal debris means that scrapping finished parts becomes inevitable. Debris develops and is sealed inside the part. When there is some highly detailed feature, i.e., fine fin pitches, stray material can become lodged between the fins reducing liquid flow and decreasing thermal performance in an unpredictable manner.  In some cases the additional debris only becomes loose over time and the restriction becomes apparent at that future time. To avoid this, additional quality assurance tests and cleaning processes can be implemented. This again is just adding cost.

Are there other alternatives? One method is called FSW – friction stir welding. The process (welding) is done by a specially ground tool in the milling machines that create a soft “plastic” state by using the spindle speed and feed rates to control the process.

friction stir welding head through material

Showing down ward pressure and rotation in friction stir welding through material

The key attribute of using FSW for heat sinks is that you are not changing the anneal of the material, so there is no need for additional annealing and eliminate the other problems that result from this process: Wasted material, Increased machining costs, Internal debris, and Additional QA testing.

In the traditional sense FSW is actually a whole lot closer to machining than welding. Once you have the proper tool, speeds & feeds, where the process control is locked down, it is a very, very, stable operation.

4 basic steps when FSW

Base material to be joined and joining tool

 

When considering companies to do FSW heat sinks for you, look for:

  1. Experience with this process – Look for a company that has done at least several hundred meters.
  2. Professional training – Has the personnel attended classes at the TWI training center in Cambridge, England? Do they have technical support from TWI for special projects like solid copper welding, welding solid aluminum and aluminum castings, or even dissimilar materials?
  3. Machining knowhow – One of the important aspects from a machining stand point is holding on to the parts during the FSW operation. The company should have experience machining aluminum for decades from very low speeds & feeds, up to speeds of 60,000 RPM, i.e. feed rates of over 350 inch/min.

Below additional history and detail about this process.

WA Technology

 

For more questions on this article contact:

Andrew Hill

Hill Technical Sales

216 West Campus Drive

Arlington Heights, IL 60004

Tel: +1- 847-255-4400 ext 12 Fax: +1-847-255-0192

You may also visit: http://www.hilltech.com/

 

 

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Hill Tech – HVR – Solar Power 2012

Hill Technical Sales will be assisting HVR this year at the solar show.

Come see us for expert assistance in the implementation of high energy resisters in your Power Electronics designs.

We will be posting photos and comments on this site during the show.

You may also contact Hill Tech at 847-255-4400 or visit www.hilltech.com

For more questions on this article contact:

Andrew Hill
Hill Technical Sales
216 West Campus Drive
Arlington Heights, IL 60004
Tel: +1- 847-255-4400 ext 12
Fax: +1-847-255-0192

You may also visit: http://www.hilltech.com/

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Hill Tech – Siba Fuse – Solar Power International 2012 – Booth # 2071

ARLINGTON HEIGHTS, ILLINOIS, USA, Saturday, September 08, 2012: Hill Tech Sales, a leader in Components for Electrical Power Conversion and Thermal Management today posted information on PV fuses for photovoltaic inverters, combiners and sub-combiners.

Hill Tech will be supporting Siba Fuse at the Solar Power International 2012 in Orlando, Florida this year, beginning Tuesday, September 10th to Thursday September 13th. This show will be held at the Orange County Convention Center – Orlando, Florida.

Siba will be showing its complete line of PV fuses:

  • Class: gPV
  • Voltage ratings: 600 to 1500VDC
  • Current ratings: 1 A to 450 A
  • Standards: UL 2579 and IEC 60 269-6
  • Approvals: E341342 and E341490 (UL)

These have high interrupt ratings up to 30kA, low I2T values, and a full range of fuse accessories from micro switches to fuse bases.

Our fuses are specifically designed for PV inverter protection, PV panel, and junction box protection. Please contact for more details as our LATEST PV Section was just released. It will appear in the new Siba 2013 catalog. Contact us at the below link for a copy of this new brochure.

If you are in the great lake region contact us to schedule a design review or product training at the booth during the show.

You may also contact Hill Tech at 847-255-4400 or visit www.hilltech.com

For more questions on this article contact:

Andrew Hill
Hill Technical Sales
216 West Campus Drive
Arlington Heights, IL 60004
Tel: +1- 847-255-4400 ext 12
Fax: +1-847-255-0192

You may also visit: http://www.hilltech.com/

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Cold-plate using internal extruded liquid channel paths

ARLINGTON HEIGHTS, ILLINOIS, USA, Friday, September 7, 2012: Hill Tech Sales, a leader in Components for Thermal Management and Electrical Power Conversion today posted information on cold-plate using internal extruded liquid channel paths.

Extruded liquid channel base, gasket and manifold

This is a construction example showing the extruded liquid channel base, with gasket interface and manifold connections

 

Typical flow path in cold plate, aluminum heat sink, manifolds show on edge of chiller plate

Choose among these four standard extruded liquid channel aluminum heat sink bases, in order to create your own custom configuration. Liquid cooled cold-plate can be up to 60 inches long.

This is a highly advanced, dependable liquid cooling technology utilizing internal liquid channels extruded into the cold-plate. No longer is expensive drilling and fabricated processes required. This extrusion technology overcomes past size limitations and comes in four standard sizes; lengths up to 60 inches!

Standard extruded channel alumium heat sink bases, cold-plate.

Standard extruded channel aluminum heat sink bases, liquid cooled cold-plate.

These can be configured in a number of parallel and series flow options provide an optimal thermal solution. The liquid channels locations were determined in order to accommodate almost all power semiconductors.  In addition, we can enhance thermal performance by using specifically designed turbulators which increase the flow rate in the fluid channel with only a minute increase in back pressure. Custom designed can a provided for specific thermal challenges.

We also provide other advanced thermal dissipation solutions:

  • VBA – Vacuum brazed cold-plate assemblies
  • Friction Stir Welding for air-cooled and liquid cooled cold plates
  • Copper cold plates
  • Heat pipes for High power industrial use: 30kW + heat pipe assemblies
  • Heat exchangers
  • Air-cooled bonded fin
  • Air-cooled pressed fin

 For more questions on this article contact:

Andrew Hill
Hill Technical Sales
216 West Campus Drive
Arlington Heights, IL 60004   
Tel: +1- 847-255-4400  ext 12
Fax: +1-847-255-0192    

You may also visit: http://www.hilltech.com/

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