Company News

E Preston Electrical Expands Franchises and Goes Online


E. Preston (Electrical) Ltd was established in 1980 as a specialist distributor of switches and electrical components.  Beginning with only 3 franchises the company currently has over 40 different franchises and holds approximately half a million pounds worth of stock.

Component Photo

Now in the third generation of family ownership E Preston Electrical continues to grow and build on traditional values.

“We work hard for our customers to get the best products at the best prices while providing exceptional customer service.  We always do what we say we will, even if that is just a call back,” says Mark Preston, MD.

This is a principle that was rooted in the business from its inception over 30 years ago by founder, and grandfather to the current directors, Ernest Preston.

Although there is still a great emphasis on these traditional values the company has embraced new technology in all of its business operations and now launches a new digital venture.  The new interactive e-shop is aimed at increasing accessibility to existing and new customers.

“We have access to the latest technology from our suppliers,” says Matthew Preston, sales director. “We want to make dealing with E Preston as easy as possible.  We will continue to visit new and existing customers, and speak to them on the telephone, but with eprestononline we can offer them access to our company whenever they want.”

Click AwayThe new eShop will allow customers to log in to their own portal to view orders, print off documents such as acknowledgements and invoices, and allows them to place repeat orders.  Data sheets and supplier catalogues will also be readily available.

The company believes it maintains its position as a traditional company – or more appropriately, a modern company with traditional values.


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Schurter RTS – Reflowable Thermal Switch

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• Prevents power semiconductors from thermal runaway
• Supports up to 60 VDC applications
• Reflow solderable at 260 °C
• Customer-specific version with shunt or overcurrent fuse
• Smallest dimensions

Schurter introduces its new RTS. The RTS is a particularly compact overtemperature protection device using advanced SMD technology. It is suited for the highest demands of protection in power semiconductors.

RTS stands for “Reflowable Thermal Switch”. It was developed to protect highly integrated power semiconductors like MOSFETs, ICs, IGBTs, Triacs, SCRs, etc. from overheating. Before mechanical activation, the RTS can be mounted using conventional reflow soldering techniques with temperature profiles up to 260 °C.

Mechanical Activation
After having the RTS reflow soldered on a PCB, mechanical activation arms the RTS for tripping at 210 °C. This activation can be done manually or by fully automated means. In contrast to electrical activation, the RTS activation status is clearly and immediately visible to the installer. Furthermore, the third additional contact required for electrical activation is thereby eliminated.

Compact Dimensions, High Load Capacity
The new type of overtemperature protection shines with the smallest dimensions and highest load capacity. Operating currents up to 100 A at rated voltages of up to 60 VDC can be handled by the RTS, which is just 6.6 x 8.8 mm in size. Customer-specific variants are available with an integrated shunt or an additional overcurrent fuse. These further integrated functions are resulting in less space consumed on the printed circuit board. The Reflowable Thermal Switch meets the high reliability requirements of AEC-Q200 and MIL-STD.

Protection Against Thermal Runaway
Thermal runaway refers to the overheating of a power semiconductor due to a self-reinforcing, heat-producing process. The reasons for this are the ever increasing power density and the trend towards miniaturization of electronic circuits.

RTS protects power semiconductors not through a logic circuit but rather through basic laws of physics. In case of a thermal runaway, the RTS reliably interrupts the circuit precisely at the well-defined temperature.

Technical Data
• Rated Voltage 60 VDC
• Tripping temperature 210 °C
• Operating current up to 100 A


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Hylec’s Comprehensive Range of PCB Terminal Blocks

Hylec’s comprehensive range of PCB terminal blocks is suitable for virtually every application.

Enabling secure transmission of signals, data and power to PCBs, Hylec’s wide range of terminal blocks feature a space-saving connection method ideal for multiple OEM applications in consumer, processing and industrial applications. In virtually every type and style, as well as standard though-hole mounting and wire protected designs, there are plug & socket (right-angled and vertical), board-to-board (pluggable) and screwless, push-wire terminal blocks, plus rising clamp PCB terminal blocks in single, double and triple-decker styles which save valuable board space.


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Schurter Type FMAB NEO with Optionally Available Overvoltage Protection (Varistors)

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• optional overvoltage protection
• very compact design
• attractive price/performance ratio

Schurter expands the successful range of chassis mounted filters for single-phase systems FMAB NEO with optionally available overvoltage protection (varistors). This is increasingly in demand, especially in regions with many thunderstorms. The single-stage filter series has a compact design with high performance at the same time.

Overvoltage pulses (e. g. lightning) often have a devastating effect on electronic circuits. This can range from malfunctions to complete destruction. In response to special customer requests, SCHURTER has therefore extended its popular and successful FMAB NEO filter family with varistor variants for surge protection. These variants are available on request. They have ENEC approvals for the entire current range as well as UL/CSA approvals from 1 A to 20 A.

The single-stage filter series has steel housings with a closed bottom. This effectively shields the filter, no matter how it is installed. The series is suitable for applications with high symmetric interferences – such as devices with semiconductors that control large outputs (e.g. professional coffee machines, devices with hot water supply, industrial electronics). The particularly compact filters are also ideally suited for medical and household appliances.

The filter series is available with push-in fittings or threaded bolts. Optionally, there are versions with stranded cable connection. All models have a metal flange for easy screw mounting on the housing.

The series is designed for currents from 1 A to 60 A at 250 VAC in accordance with IEC and UL standards. It has the ENEC and cURus approvals and is suitable for applications in accordance with IEC 60950. Variants with small leakage currents <80 μA (M80) or without leakage current <5 μA (M5) are available for medical devices in accordance with IEC / UL 60601-1.


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Schaffner Document: EMC in Medical Applications

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When Every Heartbeat Counts

Holger Urban, Product Marketing Manager, Schaffner International AG

It is apparent that the medical electronics market continues to grow and that this trend is unlikely to slow down any time soon. Every person who has access to advanced medical care will try to get the best support available and the best treatment possible to increase their quality of life. Due to changes in demographic and social standards, we expect further increases in demand on medical infrastructure within the next few years.

The ability to design customer centric solutions for home care or even robot-aided surgery drives engineering to the edge and to technologies inconceivable just decades ago. The central challenge to designers is to improve health without applying any additional risk to the patient.

EMC is now considered to be one of the most important design aspects that any new electrical or electronic system design needs to fulfill. It is therefore essential that designers should consider integrating EMC filters as soon as possible in the development phase. Selecting the right EMC filter could save time and prevent additional costs in later stages of the design approval process.

A good example of a medical application with limited space is automated syringe pump. Such pumps are directly attached to the patient through an insulating plastic hose. The medication delivery must be programmable and repeatable; this means that the control logic has to be reliable. That’s why EMC matters in order to ensure the pumps continue to operate as intended without interfering with (or being affected by) other pumps and equipment operating nearby (within a hospital for example). Therefore relevant EMC and safety standards need to be fulfilled. The medical Standard IEC60601-1 focusses on major safety points; some of these are applicable to the mains power entry where Schaffner has a range of solutions.

Specifying Components for Fulfillment of IEC60601-1

Here Schaffner offers a level of product certification which helps designers to meet the safety requirements of European and U.S. legislations. The approval certificate for Schaffner Filters according to IEC60939-3 includes a section where the filters compatibility to fulfill the requirements of IEC60601-1 is stated.

“The FN92XX filters (B-types in particular) comply with the requirements of the EN/IEC 60601-1 standard regarding creepage and clearance distances, leakage current and voltage withstand.”

Medical EMC filters also have to be designed to allow the customer to fulfill MOPP and MOOP (Means of patient and means of operator protection) for any medical application. Depending on the level of insulation needed, design of a custom filter solution can be considered.

The leakage current definition for electrical medical devices is an important topic which has the same purpose of reducing the risk to the patient. There are number of different connections to consider. The most severe level within the standard is CF (Class C floating type connection suitable for cardiac application) applied part, which is limited to 10µA in normal condition and 50µA in a single fault condition. Considering parasitic effects in a system the filter should not introduce any additional leakage current. However in less critical applications, EMC filters with very low leakage current can be considered as well. Such filters have higher performance compared to filters without any leakage currents. Leakage currents are directly related to the value of capacitors used in filters connected between Lines to Protective Earth (PE) (Y- Capacitors or Cy).

Performance Levels with Reduced Leakage Current

Schaffner offers standard solutions for different levels of leakage current requirements. In general the solution for medical applications is the so called B-type filters. These filters do not have any capacitance to PE and therefore do not add any leakage current to the system. It must be noted that the overall leakage current for the whole system needs to be determined, even with a filter which does not introduce any leakage current.

With removal of (Cy) capacitance to PE, the overall performance of the filter is reduced compared to the standard filter with Cy. Schaffner also offers so called EB-type filter to compensate some of lost performance as a result of no Cy.

In addition to the performance enhancement, EB-type filters increase immunity to electrical fast transients compared to the B-type. This will help customers comply with the IEC/EN61000-4-4 immunity tests.

Therefore Schaffner EB-Type Filters can be the best performing filters available in its class for a reliable medical Electrical design.

To conclude, EMC filters for medical applications should:

– fulfill the most stringent leakage current regulations
– offer the best size vs performance
– be designed for typical usage in medical environment

Overall its clear devices should help to increase the health of patient and should not pose any potential risk when applied to a human body. With a Schaffner filter, customers can easily solve their EMC issues and get products certifications without applying any additional risk to the patient.

Schaffner not only offers a number of “off the shelf” EMC filtering solutions for medical applications but also works closely with customers who require customized solution.

Holger Urban Product Marketing Manager
+41 32 681 67 10 (direct)

Frank Almer Manager Marketing Communication
+41 32 681 68 80 (direct)

Schaffner EMV AG
Nordstrasse 11
4542 Luterbach
T +41 32 681 66 26
F +41 32 681 66 41


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Schurter IEC Power Entry Module Series 6200, 6202 and 6205 with V-Lock Cord Retention and Enhanced Glow Wire Resistance as Standard Features

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The power entry module series 6200, 6202 and 6205 are now equipped as standard with the V-Lock cord retention feature and are made of new material, whereby the components meet the increased glow wire tests according to IEC 60127-6 Edition 2 and IEC 60335-1 for appliances in unattended use.


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Honeywell Announces Product Upgrade to Micro Switch SZL-VL Series Limit Switch


Honeywell is pleased to announce an upgrade to the Micro Switch SZL-VL Series Limit Switch effective May 2017.

The new product features include the addition of positive opening contacts (side rotary version only), enhanced sealing level to IP67; NEMA 1, 12, 13, extended the temperature range, and added CCC certification.

The upgraded design includes modified seals, housing and a new design cable gland to improve seal performance. The housing design and mounting hole pattern remain the same. Any dimensional changes do not exceed more than 1mm.

These product enhancements will allow the potential for use in wide variety of applications as well as bring more value to our customers.

The upgrades to the SZL-VL Series require that we introduce new part numbers and obsolete the existing SZL-VL part numbers.

Value to Customers
Honeywell Micro Switch SZL-VL-S Series Miniature Limit Switches have user-friendly interfaces and may be used in a broad range of applications to help meet the challenges of many industrial environments. A variety of actuators fit on the same platform reducing the need to use various kinds of mounting hardware.

With robust environmental ratings, the SZL-VL-S is protected for all kinds of industrial applications. IP67 indicates that the SZL-VL-S is protected against the effect of immersion in water between 15 cm and 1 m. The competition standard is IP65 which can only withstand low pressure spray and jets of water. The electrical rating of 10 A permits the SZL-VL-S switch to be used with heavier electrical loads than competitors.

Key Features
* Approvals: CCC, CE, cULus
* Sealed to IP67, NEMA 1, 12, 13
* Snap-action contacts
* Die-cast metal housing with glass-filled, flame-retardant thermoplastic cover
* Stainless steel levers with either steel and nylon rollers
* Variety of actuators
* Positive-opening contacts (plunger version only)
* RoHS compliant
* Utilization category:
>AC-15 A300 (380 Vac/0.5 A)
>DC-13 Q300 (220 Vdc/0.05 A)
* Mechanical life rating: 10 million cycles
* Electrical life rating: 0.5 million cycles

Potential Applications
* Commercial appliances
* Exhaust and fume hood door monitoring
* Lift mechanisms inside high-density parking garages
* Logistic facilities
* Machine electrical interlock
* Machine position sensing
* Ramp up and down position monitoring
* Scissor and man lifts
* Vending machines


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Hylec-APL: 80A Rotary Isolator Switches / TeeTube / Debox

Completely Submersible TeeTube TH381 Connectors; 80A Rotary Isolator Switch; Debox 100% Tool-Free Junction Boxes

Hylec is well-known for its extensive ranges of junction boxes, terminal blocks, door enclosures, weatherproof connectors and HVAC components, and among these is the new 80A Rotary Isolator switch, the latest addition to the ROTARY ISOLATOR range of AC and DC switches for industrial and commercial buildings. IP67-rated and able to withstand water up to a depth of 1 metre, ROTARY ISOLATOR switches enable fast shut down in emergencies and ensure the circuit is completely de-energised for routine service and maintenance. With plenty of internal space for ease of installation, this range offers best-value/performance on the market.

Another new product that has taken the trade by storm since its introduction in April is the TH381 TeePlug, a completely submersible waterproof micro-connector for underwater and harsh environment installations. IP68/IP69K-rated and only 14mm in diameter, the TeePlug TH381 Series provides complete protection against high pressure water jets too. Its push-pull design installs up to 80% faster than competitive waterproof connectors. The TH381 Series suits outdoor lighting applications, such as architectural lighting, underwater lighting, road sign and billboard illumination and connection of exterior and interior Class 2 electrical devices.

The Debox range of in-line junction boxes, including the 100% tool less Debox SL can be assembled in a few seconds. It is supplied complete with a 16A, UL and VDE-approved, 4-pole screw-less push wire terminal block, DeboxSL joins flat or round profile cable and includes everything to save electricians on-site installation time and reduce costs. No tools are required: after inserting the cables and closing the included cable clamps, the lid is simply snapped shut and held with the supplied locking clip. This innovative cable junction box from Hylec-APL is IP20 protected, flame retardant to UL94V-0, and suits internal applications, including ring main lighting, LED lighting and power.


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Hylec-APL Launches New DEDSS Series Lockable IP66 IK10 Stainless Steel Enclosures for Challenging Environments


Time-saving “everything supplied” kit; suits corrosive and hygienic environments; six sizes available

Hylec-APL, the specialist supplier and manufacturer of electrical and electronic components and enclosures, today announces its new DEDSS Stainless Steel Series of lockable, solid door enclosures specially designed to provide high-quality, secure, cost-effective protection for specialist and demanding electronic and electrical installations. The DEDSS Enclosure Series is IP66 rated and protects contents against water and dust, as well as being able to withstand impact to IK10 specifications and extremes of temperature ranging between – 20degC and +55degC. Suitable applications for DEDSS enclosures include corrosive environments, such as the chemical and petrochemical industries, and environments where strict hygiene is required, for example, the agro food sector.

The rugged DEDSS enclosures range is manufactured from grade 304 stainless steel and supplied as a complete kit. This includes a metal lock and key, a 2mm galvanised steel back plate, and external mounting feet and spacers. In addition, DEDSS enclosures come complete with an earth strap pre-wired and fitted between the door and the housing to save valuable installation time.

This comprehensive range encompasses six different sizes, ranging from 300mm high x 200mm wide x 150mm deep to 500mm high x 500mm wide x 200mm deep, so offering a wide choice capable of accommodating most installations. Many accessories that fit the DEDSS range are available from Hylec: cable glands, Kwik-Fix cable glands, venting elements, contactors/thermal overloads, filter fans and other fans.

Steve Robbins, Sales Director comments: “The DEDSS range provides the perfect solution for protecting delicate components in environments that demand very high standards of security and cleanliness, for example where hygiene must be maintained, such as hospitals, dental and veterinary practices, in addition to a whole host of other industries, such as food manufacturing.”


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Schurter Fuse SHT 6.3×32 and SHT 6.3×32 Pigtail

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Schurter offers a robust, compact and cost-effective cartridge and pigtail fuse SHT 6.3×32 for high voltages and currents. The high breaking capacity up to 3500 A at a nominal voltage of 250 VAC opens the fields for applications for commercial electric cooking appliances in accordance with UL 197.

Schurter offers the SHT 6.3×32 in ten rated currents between 1 and 8 A. The high breaking capacity makes the fuse outstanding. In addition to a wide range of industrial applications the SHT 6.3×32 is particularly suitable for a large number of applications in electrical cooking appliances according to UL 197 standard for protection of 1- to 3-phase systems.

Schurter offers the SHT 6.3×32 as a fuse link and a pigtail version. Fuse links are suitable for mounting in clips and fuse holders, which makes it possible to quickly replace the fuse without soldering. SCHURTER offers the suitable clips (CQP, OG-Clip, OGD) and fuse holders (FEU FUS, FEC, FUL, FUA and FUP) for this purpose.

The most important competitor products are bigger in size (e.g. 10.3×38) and therefore more cost-intensive. That allows Schurter to offer the SHT 6.3×32 and SHT 6.3×32 Pigtail as a replacement product which will reduce size, weight and cost.

Technical Specifications
– High rated voltage of up to 500 VAC
– High breaking capacity of 3500 A @ 250 VAC / 1500 A @ 500 VAC
– Rated current range from 1 to 8 A
– Time lag characteristic T
– Ceramic housing

Application Areas
– Commercial electric cooking appliances according to UL 197
– Photovoltaics
– Frequency converters
– Power electronics
– 3-phase applications


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Contact E Preston Electrical

tel: +44(0) 161 339 5177


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