Terminate and Connect Electrical Wiring and Electronic

FUSE 

Once you design a simple circuit on electronics, it is important to include a   fuse in the primary or secondary of a transformer 

Wires and Cable 

A wire is a single slender rod or filament of drawn metal. This definition restricts the term to what would ordinarily be understood as solid wire. The word “slender” is used because the length of a wire is usually large when compared to its diameter. If a wire is covered with insulation, It is an insulated wire. Although the term “wire” properly refers to the metal, it also includes the insulation. 

Switch and its function  

Switch is a device used to break an electric current or transfer it to another conductor. Switches are commonly used to open or close a circuit. Closed is the ON position, while open is OFF position. Normally, switch is installed in series with the line carrying current from the power source to the load.   

This is the most common component in electronics. It is used mainly to control current and voltage within the circuit. You can identify a simple resistor by its simple cigar shape with a wire lead coming out of each end. It uses a system of color coded bands to identify the value of the component (measured in Ohms) 

Capacitors, or "caps", vary in size and shape ‐ from a small surface mount model up to a huge electric motor cap the size of paint can. Whatever the size or shape, the purpose is the same. It stores electrical energy in the form of electrostatic charge. 

It is charged with a magnetic field and when that field collapses it produces current in the opposite direction. Inductors are used in Alternating Current circuits to oppose changes in the existing current. 

Diodes are basically a one‐way valve for electrical current. They let it flow in one direction (from positive to negative) and not in the other direction.   Most diodes are similar in appearance to a resistor and will have a painted line on one end showing the direction or flow (white side is negative). If the negative side is on the negative end of the circuit, current will flow. If the negative is on the positive side of the circuit no current will flow. 

LEDs are simply diodes that emit light of one form or another. They are used as indicator devices. 

Example: LED lit equals machine on. They come in several sizes and colors. Some even emit Infrared Light which cannot be seen by the human eye. 

The transistor is possibly the most important invention of this decade.   It performs two basic functions. 

1) It acts as a switch turning current on and off.

2) It acts as an amplifier. This makes an output signal that is a magnified version of the input signal. 

Integrated Circuits, or ICs, are complex circuits inside one simple package. Silicon and metals are used to simulate resistors, capacitors, transistors, etc. It is a space saving miracle.   

To pass current very easily from one part of a circuit to another. 

A 'blob' should be drawn where wires are connected (joined), but it is sometimes omitted. Wires connected at 'crossroads' should be staggered slightly to form two T‐ junctions, as shown on the right. 

In complex diagrams it is often necessary to draw wires crossing even though they are not connected. I prefer the 'bridge' symbol shown on the right because the simple crossing on the left may be misread as a joint where you have forgotten to add a 'blob'! 

Supplies electrical energy. The larger terminal (on the left) is positive (+). A single cell is often called a battery, but strictly a battery is two or more cells joined together. 

Supplies electrical energy. A battery is more than one cell. The larger terminal (on the left) is positive (+). 

Supplies electrical energy. DC = Direct Current, always flowing in one direction. 

Supplies electrical energy. AC = Alternating Current, continually changing direction. 

A safety device which will 'blow' (melt) if the current flowing through it exceeds a specified value. 

Two coils of wire linked by an iron core. Transformers are used to step up (increase) and step down (decrease) AC voltages. Energy is transferred between the coils by the magnetic field in the core. There is no electrical connection between the coils. 

A connection to earth. For many electronic circuits this is the 0V (zero volts) of the power supply, but for mains electricity and some radio circuits it really means the earth. It is also known as ground. 

A transducer which converts electrical energy to light. This symbol is used for a lamp providing illumination, for example a car headlamp or torch bulb. 

A transducer which converts electrical energy to light. This symbol is used for a lamp which is an indicator, for example a warning light on a car dashboard. 

A transducer which converts electrical energy to heat. 

A transducer which converts electrical energy to kinetic energy (motion). 

A transducer which converts electrical energy to sound. 

A transducer which converts electrical energy to sound. 

A coil of wire which creates a magnetic field when current passes through it. It may have an iron core inside the coil. It can be used as a transducer converting electrical energy to mechanical energy by pulling on something. 

A push switch allows current to flow only when the button is pressed. This is the switch used to operate a doorbell. 

This type of push switch is normally closed (on); it is open (off) only when the button is pressed. 

SPST = Single Pole, Single Throw. An on‐off switch allows current to flow only when it is in the closed (on) position. 

SPDT = Single Pole, Double Throw. A 2‐way changeover switch directs the flow of current to one of two routes according to its position. Some SPDT switches have a central off position and are described as 'on‐off‐on'. 

DPST = Double Pole, Single Throw. A dual on‐off switch which is often used to switch mains electricity because it can isolate both the live and neutral connections. 

The proper wire size is critical to any electrical wire installation. Wire sizing indicates the diameter of the metal conductor of the wire and is based on the American Wire Gauge (AWG) system. 

Wires that are not properly matched to the amperage of the circuits they serve can create a notable risk of short circuit and fire. 

Most interior wiring is done with non-metallic, or NM, cable—also known by the popular brand name Romex. NM cable is made of three or more wires wrapped inside a flexible plastic jacket, or sheathing. It is used for most interior circuits, such as those for outlets, switches, light fixtures, and appliances. 

Color coding is used both on the outer sheathing of bundled electrical cables and on the individual conduction wires within cables or inside the conduit. Understanding this color coding can help you identify what the wiring is used for and helps maintain consistency within an electrical system. 

Electrical wires and cables have markings stamped or printed on their insulation or outer sheathing. These markings provide important information about the wiring and insulation, including the wire size and material, the type of insulation, the number of wires contained (inside a cable), and any special ratings or characteristics of the wire. 

Standard electrical cable is designed to be run indoors, where it stays dry and is protected by wall, ceiling, or floor structures. For outdoor projects or when running wiring underground, you must use direct-burial cable, which can be installed underground with or without conduit (depending on local building code rules). With direct-burial cable, the individual conducting wires are embedded in solid vinyl to fully protect them from moisture. 

Stripping electrical wire involves removing the plastic insulation surrounding the wire's metal core. It's important to do this carefully so there is no damage to the metal. The procedure is simple but requires a special wire stripping tool and an understanding of how to use it. 

When running individual electrical wires inside conduit, there is a limit to how many wires are allowed. The maximum allowable number is known as the "fill capacity," and this depends on several factors, including the size of the conduit, the gauge of the wires, and the conduit material. Metal (EMT), plastic (PVC), and flexible conduit all have different fill capacities, even when they're nominally the same size. 

The electrical panel, or service panel, is the power distribution point of a home electrical system. This is where all of the individual circuits of the house get their power and where they are protected by breakers or fuses. 

An electrical disconnect switch provides a means to shut off the power to a home's electrical system from an outdoor location. It is typically mounted below the electric meter, either on the side of a home or on the utility company's power pole. This is a service disconnect switch. 

Surface mount soldering techniques 

This kind of joint is commonly used to join two or more conductors inside the junction box. It is suitable for service where there is no mechanical stress when wires are to be connected in an outlet box, switch, or conduit fitting 

This method of wrapping is generally used on small cables because the strands are flexible and all can be wrapped in one operation. 

Joint all the splices discussed up to this point are known as butted splices. Each was made by joining the free ends of the conductors together. Sometimes, however, it is necessary to join a branch conductor to a continuous wire called the main wire. Such a junction is called a tap joint. 

This is used where the tap wire is under considerable tensile stress circuit.

This is used as a temporary tap usually done in constructions sites. The easy twist will facilitate tap wire movement. 

This is a two-tap wire turned simultaneously and is used where the two tap wire is under heavy tensile stress. 

This is the most widely used splice or joint in interior wiring installation to extend the length of wire from one point to another. 

This is used extensively for outside wiring to extend the length of wire from one end to another. 

The same application is done as in plain tap and the only difference is that this tap is a combination of two plain taps place side by side with each other. 

This is used on large solid conductors where it is difficult to wrap the heavy tap wire around the main wire.

Also known as a VOM (Volt-Ohm meter), a multi-meter is a handheld device that combines several measurement functions (such as voltage, current, resistance and frequency) into a single unit.

Multi-meters are mainly used to troubleshoot electrical problems in a wide array of industrial and household devices such as electronic equipment, motor controls, domestic appliances, power supplies, and wiring systems.

Most commonly referred to as simply a “megger”, a megohmmeter is a special type of ohmmeter used to measure the electrical resistance of insulators. 

Resistances values by megohmmeters may range from several megohms to several million megohms (teraohms). Megohmmeters produce high voltages via battery powered internal circuitry or a manually operated generator with outputs ranging from 250 to 15,000 volts.

Megohmmeters are one of the most frequently used pieces of test equipment and can be used to measure the insulation of various types of apparatus such as circuit breakers, transformers, switchgear and cables.

Often called a DLRO in the field, the low-resistance ohmmeter is used for making high-precision resistance measurements below 1 ohm. Low-Resistance ohmmeters produce low voltage DC currents via battery power with outputs of up to 100A. 

Resistance measurements are achieved with four terminals, called Kelvin contacts. Two terminals carry the current from the meter (C1, C2), while the other two allow the meter to measure the voltage across the resistor (P1, P2). With this type of meter, any voltage drop due to the resistance of the first pair of leads and their contact resistances is ignored by the meter. 

Dielectric withstand (or hipot) testing checks for good insulation in medium and high-voltage apparatus, the opposite of a continuity test. Insulation is stressed above nominal values to ensure minimal current leaks from the insulation to ground.

Hipot test sets consist of a high voltage lead, a return lead, and a ground lead. The high voltage lead is connected to the device under test with all other components grounded and the resulting current is measured through the return.

A high current test set may consist of two pieces known as a “control unit” and an “output unit”, or these functions may be combined in a single package. Low voltage, high current outputs are used for primary-injection testing of low voltage circuit breakers.

The high current or “primary-injection” test set consists of large transformers that step down line voltage (ex. 480V) to a very low level, such as 2-15V. The large reduction in voltage allows for a large increase in available current output (15kA+), especially for a short duration.

Circuit breakers with solid state and microprocessor trip units can be tested by injecting secondary current into the trip unit directly rather than passing primary current through the CT’s using a high current test set. The main shortcoming of the secondary current injection test method is that only the solid-state trip unit logic and components are tested.

Secondary test sets are designed by trip unit manufacturers to be used with a single style or family of trip unit using a proprietary connection. Test kits can range from simple hand held, push button style in design to more sophisticated “suitcase” units that operate similar to a primary injection test set.

These are power system simulators used for testing protection devices used in industrial and power systems. Relay test sets are fitted with multiple sources to test solid-state and multi-function numerical protection, each voltage and current channel is operated independently to create different power system conditions. 

Power Factor Test Sets provide a comprehensive AC insulation diagnostic test for high voltage apparatus, such as transformers, bushings, circuit breakers, cables, lightning arrestors, and rotating machinery.

Test voltages are generally 12kV and below, the power factor test set measures voltage and current of the device under test using a reference impedance. All reported results – including power loss, power factor, and capacitance – are derived from the vector voltage and current.

Winding resistance measurements are an important diagnostic tool for assessing possible damage to transformer and motor windings. Winding resistance in transformers will change due to shorted turns, loose connections, or deteriorating contacts in tap changers. 

Measurements are obtained by passing a known DC current through the winding under test and measuring the voltage drop across each terminal (Ohm's Law). Modern test equipment for this purposes utilizes a Kelvin bridge to achieve results; you might think of a winding resistance test set as a very large low-resistance ohmmeter (DLRO). 

The TTR test set applies voltage to the high-voltage winding of a transformer and measures the resulting voltage from the low voltage winding, this measurement is known as the turns ratio. In addition to turns ratio, the units measure excitation current, phase angle deviation between the high- and low-voltage windings and percent ratio error.

Transformer turns ratio test sets come in a variety of styles and test connections, however all turns ratio testers have at least two high leads and two low leads. The excitation voltage of a TTR test set is generally less than 100V.

CT test sets are small, multi-function units designed to perform demagnetization, ratio, saturation, winding resistance, polarity, phase deviation, and insulation tests on current transformers. High-end CT test equipment can directly connect to multi ratio CT’s and perform all tests on all taps with the push of a button and without changing leads.

Current transformers can be tested in their equipment configuration, such as being mounted in transformers, oil circuit breakers or switchgear. Modern CT with multiple voltage and current outputs can double as a relay test set when operated with a laptop computer.

Traditional field testing of vacuum interrupters utilizes the hi-potential test in order to evaluate the dielectric strength of the bottle, this test produces a go/no-go result that does not determine when, or if, the gas pressure inside the bottle has dropped to a critical level. Unlike the hipot test, testing vacuum interrupters utilizing magnetron atmospheric condition (MAC) principles can provide a viable means for determining the condition of vacuum interrupters prior to failure. 

The ground resistance test set works by injecting a current into the earth between a test electrode and a remote probe, measures the voltage drop caused by the soil to a designated point, and then use Ohm's Law to calculate the resistance.

Ground resistance test sets come in a variety of styles with the most common being the 4-terminal unit for soil resistivity testing and the 3-terminal unit for fall-of-potential testing. Copper rods or similar stakes are used to make contact with the earth along with spools of small stranded wire to cover long distance measurements.

Power recorders are devices used to collect voltage and current data which can be downloaded into software in order to analyze electrical system conditions. These are troubleshooting tools used to pinpoint electrical problems such as voltage swells, sags, flicker and poor power factor.

Power recorders may also be used to measure power consumption over a period of time, which is useful for engineers planning to expand a system or customers who wish to audit their energy bills.