IN FOCUS: THE ELECTROLYTIC CAPACITOR

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DEFINITION

“An electrolytic capacitor is a polarized capacitor which uses an electrolyte to achieve a larger capacitance than other capacitor types”

 

WHAT IS AN ELECTROLYTIC CAPACITOR?

An electrolytic capacitor is a type of capacitor that uses an electrolyte to achieve a larger capacitance than other capacitor types. An electrolyte is a liquid or gel containing a high concentration of ions. Almost all electrolytic capacitors are polarized, which means that the voltage on the positive terminal must always be greater than the voltage on the negative terminal

Electrolytic capacitors can be either wet-electrolyte or solid polymer and are commonly made of tantalum or aluminum.

 

Capacitance drift

 

The capacitance of electrolytic capacitors drifts from the nominal value as time passes, and they have large tolerances, typically 20%.  Tantalum electrolytic capacitors can be made with tighter tolerances, but their maximum operating voltage is lower so they cannot be always used as a direct replacement.

 

Polarity and safety

 

Due to the construction of electrolytic capacitors and the characteristics of the electrolyte used, electrolytic capacitors must be forward biased. This means that the positive terminal must always be at a higher voltage than the negative terminal. If the capacitor becomes reverse-biased (if the voltage polarity on the terminals is reversed), the insulating aluminum oxide, which acts as a dielectric, might get damaged and start acting as a short circuit between the two capacitor terminals. This can cause the capacitor to overheat due to the large current running through it. As the capacitor overheats, the electrolyte heats up and leaks or even vaporizes, causing the enclosure to burst. This process happens at reverse voltages of about 1 volt and above. To maintain safety and prevent the enclosure from exploding due to high pressures generated under overheat conditions, a safety valve is installed in the enclosure. It is typically made by making a score in the upper face of the capacitor, which pops open in a controlled manner when the capacitor overheats. Since electrolytes may be toxic or corrosive, additional safety measures may need to be taken when cleaning after and replacing an overheated electrolytic capacitor.

 

There is a special type of electrolytic capacitors for AC use, which is designed to withstand reverse polarisation. This type is called the non-polarized or NP type.

Aluminum electrolytic capacitors are made of two aluminum foils and a paper spacer soaked in electrolyte. One of the two aluminum foils is covered with an oxide layer, and that foil acts as the anode, while the uncoated one acts as a cathode. During normal operation, the anode must be at a positive voltage in relation to the cathode, which is why the cathode is most commonly marked with a minus sign along the body of the capacitor. The anode, electrolyte-soaked paper and cathode are stacked. The stack is rolled, placed into a cylindrical enclosure and connected to the circuit using pins. There are two common geometries: axial and radial. Axial capacitors have one pin on each end of the cylinder, while in the radial geometry, both pins are located on the same end of the cylinder

Read more http://www.capacitorguide.com/electrolytic-capacitor

 

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IN FOCUS: THE THERMISTOR

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PURPOSE

A thermistor is a semiconductor device with an electrical resistance proportional to temperature. The name is formed from a combination of the words “resistor” and “thermal.” Thermistors come in two types: one type is PTC, which stands for positive temperature coefficient of resistance; the other is NTC, which stands for negative temperature coefficient of resistance.

SIGNIFICANCE

All conductors have an electrical resistance proportional to their temperature. Everyday devices such as toasters, heaters, hair dryers and light bulbs operate on this principle. Thermistors are created to deliberately optimise this property and are more temperature sensitive than regular resistors. This sensitivity enables them to determine thermal measurements to within ranges of plus or minus .05 per cent to plus or minus .02 per cent. This accuracy makes them very effective as thermometers and sensors.

 FEATURES

Thermistors make excellent thermometers because they are small, very stable and long lasting, in addition to being accurate. They are better at measuring certain temperatures than thermocouples. The disadvantage is that like typical semiconductors they are non-linear, so circuits must be designed with this limitation in mind. Also, unlike thermocouples, they cannot be used at extreme temperatures and are usually confined to those from zero to one hundred degrees Celsius

NTC

NTCs are the most common type of thermistor. Their temperatures vary inversely with their resistance. When the temperature increases, their resistance decreases, and when the temperature decreases, their resistance increases. Another role is that of current suppressors. Additional tasks include temperature compensation, control and indication. NTCs are made from oxides of materials such as nickel, manganese, copper, iron and cobalt. Some are also made from silicon, germanium or a combination of both.

 PTC

PTC thermistors are the opposite of NTCs. When the temperature increases so does their resistance; when the temperature decreases, their resistance does the same. They are used as thermometers or switches and also for circuit overload protection. Other uses are for light switching, heating regulation, starting motors and telecoms. PTCs are constructed using semiconductors combined with ceramics or polymers.

 USES

Thermistors have important roles in circuit operations. In medicine, thermistors are used as clinical temperature sensors, in stethoscopes and as probes during surgery. They are found in other devices where temperature detection and control is vital, such as in controlling water, steam and air. In the food service industry, this ability is used in food safety and cooking equipment. Since they regulate temperature and provide protection against overheating in circuits, they can be found in cars, cell phones, computers, amplifiers, home appliances and more.

thermistor

EXPRESS YOURSELF: MAKE US YOUR MANUFACTURER

Choosing a custom wire or cable assembly supplier is a huge decision. With so many companies who specialise in this niche of the electronics manufacturing industry, out there, it is difficult for a potential customer to differentiate between them.

Ultimately you want a supplier that is efficient, good value for money, productive, reliable and that can meet the requirements of your job specification.

However, finding one that exceeds your requirements, and offers an impeccable quality of product, combined with the most competitive of lead times is often a tricky task.

That’s where we come in.

Express Assemblies has been trading for over 20 years and has a wealth of experience in this industry. With a vast product portfolio, modern production plant and an unbeatable customer service record, we like to think we are working at the ‘cutting edge’ of wire and cable manufacturing and aim to be your number one choice for all your assembled product requirements.

So what makes us stand out?

E = Evolutionary: from humble beginnings on the kitchen table to now being a certified, accredited wire and cable business, operating to over 250 customers, the company has evolved into a huge force in the wire and cable assembly market.

X = eXcellence: Working to the pinnacle of quality excellence, Express Assemblies offers a range of services to add value to your business

P = Performance: catering our business to deal with any enquiry means we are flexible and adaptable in our approach. Not only this but we strive to meet production deadlines and demonstrate consistent work process performance from start to finish.

R = Reputation: As our product portfolio continues to expand and with a rapid rate in the growth of our business, we are achieving a strong reputation as one of the leading companies in the wire and cable assembly industry. We work hard to ensure our name reaches the masses and with repeat orders from over 97% of our customer base, our reputation speaks for itself.

E = Expertise: we have experienced, extremely capable staff on hand to deal with any questions or issues you may have regarding your wire and cable assembly.

S = Skilful: Express Assemblies can help bring a concept or idea to reality using highly skilled methods and training practice.

S = Successful: We like to think we are, 20 years and still going strong.

Without you, the customers, we would have no business. We want to work with you and offer you a process that provides simple, yet highly effective solutions to all your wire and cable assembly needs.

So why not Express yourself today and choose Express Assemblies Ltd, where we make the right connections!

IN FOCUS: THE BOOTLACE FERRULE

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Using the bootlace ferrule acts as a reliable electrical connection and protects the outer conductors and wire strands of flexible stranded wire from ‘bending’ and splaying. Ferrules are available uninsulated and insulated with colour coded plastic sleeves for single or dual wire applications.

Used in various components from terminal blocks, motor drives and a range of circuit breakers, the insulated bootlace ferrule prevents conductor breakage and allows for a simple insertion into final products. Generally used as an alternative to tinning or soldered connections, the bootlace ferrule is becoming the leading choice for wire and cable termination.

At Express Assemblies Ltd, bootlace ferrules are used daily with a variety of ferrules suited for customer specifications. From uninsulated to insulated collar and twin ferrules, the need for ferruling a wire or cable is now essential for our business prospects.

Choosing the correct ferrule therefore is critical to ensure a quality connection. There are two basic versions; French and German. Categorised by colour, the ferrule is determined by the size of the wire or wire gauge [AWG].  Both systems are equally good and to be honest unless specified by the customer, go with the simplest.

Cord-End-Ferrules-chart

“Insulated ferrules also come in twin entry versions making a 2-1 termination quick and simple and we in the cable assembly business like them because they are not messy and require very little labour” 2

  1.  https://www.google.co.uk/search?q=insulated+ferrule+colour+chart
  2. http://www.electronicsweekly.com/electro-ramblings/industry-comment/only-connect-a-guide-to-insulated-ferrules-2013-02/#sthash.QaCdkzXl.dpuf 

 

We are well equipped to deal with any ferruling enquiry.

WIRES AND CABLES: THE ULTIMATE PLAYLIST

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It may not be at the top of everyone’s download list or not make number one in the album charts, but this is the definitive guide of songs and artists relevant to wire and cables. The ultimate playlist, so why not take a listen:

Artist                                                                                                                            Song

Athlete                                                                                                                    Wires

Haim                                                                                                                     The Wire

Chumbawumba                                                          Hanging on the Old Barbed Wire

Electric Wire Hustle                                                         Numbers and Steel

Leonard Cohen                                                                      Bird on the Wire

Kanye West                                                                         Through the Wire

Wire                                                                                  I Should Have Known Better

Adrenaline Mob                                                              The High Wire

Razorlight                                                                      Wire to Wire

Basic Cable Preachers                                                The View

Marty Robbins                                                              Jumper Cable Man

Eddy Grant                                                                      Electric ‘Wire’ Avenue

EXPRESS GOES GREEN

eco

All through our history, mankind has pillaged, pawned and plundered Planet Earth. Until fairly recently, most businesses didn’t give the environment a second thought; even 20 years ago, it fell off the corporate radar and was generally regarded as ‘hype’.

Much has changed. It’s become increasingly apparent that so-called ‘global development’ cannot continue unchecked, indefinitely. Issues of sustainability have moved up the political and economic agenda and they can no longer be ignored.

Pro-Activists

Today, the pressure on businesses to ‘be green’ has never been greater. As consumer awareness of environmental issues increases, so have consumer expectations. Thankfully, eco-friendly practices are becoming the norm, and green credentials are something by which we measure performance, value and success.

Now, when it comes to the environment, there’s no way that businesses can vouch ignorance. Whatever they do, be it good or bad, it will be noticed; it goes without saying that everyone wants to be noticed for the right reasons.

There’s been a distinct shift in investors’ preference for companies that intentionally ‘do more good’ rather than just ‘do no harm.’ It’s no longer enough to not be bad and avoid mass pollution and all the shocking, headline-grabbing crimes. Now, businesses are expected to be proactive and intelligent in their efforts to make the world a better place.

Good All Round

What’s good for the environment is ultimately good for business. No company can hope to have a good image without green credentials. A strong, innovative and thoughtful environmental policy gives companies a well-earned reputation for being credible, ethical and responsible.

Consumers are starting to really care about this sort of thing, and they’re more discerning than ever. The demand for environmentally-friendly products and services is strong and growing, with many willing to pay more and demonstrating loyalty and goodwill towards companies with good green credentials. You’ll also find they can open the door to greater community involvement and real engagement with the locals.

Being green is a real competitive advantage on the international playfield. Having all the right green credentials and qualifications satisfies stakeholders, reassures investors, builds stronger community relationships and provides access to new partnerships and business opportunities. It also helps businesses to attract the best employees, as many of today’s best young employees report that they’re more inclined to work for companies that are known to be environmentally-friendly.

Saving Money- and Face

Being green can save businesses a fortune. The small upfront investment required is made up for many times over by the cost savings. Being environmentally-friendly involves scrutinising every single business process in order to reduce waste and fuel consumption. Green means lean, and maximising operational efficiency will ultimately bolster the bottom line.

Finally, being green mitigates risk and saves face. New environmental legislation is being set out all the time. Organizations that are leading the way, rather than dragging behind, can be confident that they won’t land a fine, face the hassle and embarrassment of prosecution or have to fork out for higher insurance premium.

All businesses, whatever their size, culture or industry, will really benefit from being green. Those that choose not to prioritise the environment will end up green with envy at the success of their competitors

WIRE AND CABLE TYPES!

res and cables are big business. Part of our everyday existence, they have transformed and revolutionised the way that we live. Without them, there would be no mobile phones, computers, televisions, microwaves or kettles [to name a few], the importance of them often goes overlooked, but simply put how would society function in a world without wires or cables?

With the wire and cable manufacturing market estimated to grow to $200 billion by 2015, it is not only an exciting market but an extremely lucrative industry to be involved in.

  • FACT: Did you know that there are over 5000 types of wire or cable available to consumers. But with so many different ones to choose from, how do you decide which is the one for you

wire-and-cable

This post aims to simplify that process and identify a few common wire and cable types and their everyday uses

  • EQUIPMENT/HOOK-UP WIRE: Hook-up wire is small-to-medium gauge, solid or stranded, insulated wire, used for making internal connections inside electrical or electronic devices
  • TRI-RATED WIRE:  Its a high temperature, flame-retardant electrical cable designed for use in panel building
  • MAINS CABLE: A power cord, line cord, or mains cable is a cable that temporarily connects an appliance to the mains electricity supply via a wall socket or extension cord
  • SPEAKER CABLE: Speaker wire is used to make the electrical connection between loudspeakers and audio amplifiers. Modern speaker wire consists of two or more electrical conductors individually insulated by plastic or, less commonly, rubber.
  • SWITCHGEAR WIRE: A switchgear cable is a flexible electrical cable,  designed to isolate electrical equipment.
  • AUTOMOTIVE WIRE: Wire used in general automotive projects, ranging from cars to trucks, tractors etc
  • WELDING WIRE AND CABLE: A welding electrode fed into the handset from a reel
  • TELECOMMUNICATIONS CABLE: Telecommunication cables are a type of guided transmission mediums. Cables are usually known to transmit electric energy but in telecommunications fields, cables are used to transmit electromagnetic waves, they are called electromagnetic wave guides
  • SIGNAL CABLE: A signal cable is an electrical cable of one or more insulated conductors enclosed by a common conductive layer. The shield may be composed of braided strands of copper, a non-braided spiral winding of copper tape, or a layer of conducting polymer
  • FIRE CABLE: used as heat resistance cables. They are mainly used in fire alarms and emergency lighting circuits
  • FIBRE OPTIC CABLE: a cable made of optical fibres that can transmit large amounts of information at the speed of light
  • CATEGORY 5E AND 6: Category 5 cable (Cat 5) is a twisted pair cable for carrying signals. This type of cable is used in structured cabling for computer networks
  • COAXIAL CABLE: Coaxial cable, or coax, is a type of cable that has an inner conductor surrounded by a tubular insulating layer, surrounded by a tubular conducting shield
  • KYNAR/TEFZEL WIRE: special plastic material in the fluoropolymer family; it is used generally in applications requiring the highest purity, strength, and resistance to solvents, acids, bases and heat and low smoke generation during a fire event. 
  • PVC WIRE: PVC is commonly used as the insulation on electrical cables; PVC  acts as the source of the wires’ fire retardance.
  • LSZH WIRE AND CABLE: LSZH cable jacketing emits limited smoke and no halogen when exposed to high sources of heat. Protects people and equipment from toxic and corrosive gases. 
  • RIBBON CABLE: The purpose of ribbon cable is that it transmits numerous signals or electrical pulses whilst adjacent to each other, offering a space saving and efficient alternative to large amounts of connected wires and cables
  • BRAIDED CABLES: A flat cable made from bare woven wire. Similar to stranded wires, braided wires are better conductors than solid wires. Braided wires do not break easily when flexed. Braided wires are often suitable as an electromagnetic shield in noise-reduction cables
  • SILICONE WIRE: Used for typical industrial applications including food processing, packaging, refrigeration, furnaces and lighting.
  • SOLID CORE WIRE: Solid wire is cheaper to manufacture than stranded wire and is used where there is little need for flexibility in the wire. Solid wire also provides mechanical ruggedness; and, because it has relatively less surface area which is exposed to attack by corrosives, protection against the environment
  • STRANDED WIRE: Stranded wire is composed of a number of small gauge wire bundled or wrapped together to form a larger conductor. Stranded wire is more flexible than solid wire of the same total cross-sectional area. Stranded wire tends to be a better conductor than solid wire because the individual wires collectively comprise a greater surface area. Stranded wire is used when higher resistance is required
  • PTFE WIRE: In industrial applications, owing to its low friction, PTFE is used for applications where sliding action of parts is needed: bearings, gears, slide plates, etc. Also hydrophobic, this makes it suitable for use as an insulator in cable assemblies
  • POWER CABLE: A power cable is an assembly of two or more electrical conductors, usually held together with an overall sheath. The assembly is used for transmission of electrical power. Power cables may be installed as permanent wiring within buildings, buried in the ground, run overhead, or exposed. Flexible power cables are used for portable devices, mobile tools and machinery