Basic Electrical hand Tools Hand tools are tools manipulated and operated by our hands without the use of electrical energy Hand Tools and Their Uses Screw Drivers Screw drivers are made out of tools steel hardened and tempered at the tip. They come in various size and shapes, which are used to turn or drive screws with slotted heads
1.Standard Screwdriver. Standard screwdrivers are used to tighten or loosen flathead screws 2.Philips screwdriver. Philips screwdrivers are used to tighten or loosen Philip screws. 3.Stubby/close quarter screw driver. The lip is similarly shaped like the standard screw driver but with short shank blade and shorter handle which is made of plastic. 4.Offset Screwdriver. Offset screwdrivers provide means of reaching difficult flathead screws.
Pliers Pliers are used for cutting and twisting wires and to grip small parts. Pliers are available with both insulated and uninsulated handles. insulated handle pliers should be used when working on or hot conductors
1.Slip Joint Pliers Are used for a wide range of service involving gripping, turning and bending. 2.Side cutting Pliers Appropriate for cutting cable, removing knockouts, twisting wire, and deburring conduit. 3.Long Nose Pliers Appropriate for bending wire, cutting wire, and positioning small components 4.Diagonal Pliers Useful for cutting cables and wires too difficult for side cutting pliers
5.Retainer Ring Pliers Used to install retainer rings, which are a type of fastener used in assembling parts 6.Flat nose Pliers Commonly used in sheet metal to bend edges Wire Stripper Remove insulation from small diameter wire Electrician’s knife Removes insulation from cable and service conductors.
HammersClassified either as soft or hard faces. The cylindrical shape head hammer has a hard face for striking hard objects like cold chisel, star drill, and nails
1.Claw Hammer Can be used to mount electrical boxes and drive nails.Can also be used to determine height of receptacle box since most hammers are 12” in length from head to end of handle ,or can be so marked 2.Ball peen Hammer Designed for striking chisels and punches. They also may be used for riveting,shaping,and straightening unhardened metal. 3.Soft faced hammer (Rawhide or plastic hammer). Used for rewinding jobs like forming coils, assembly and disassembly of motors
Wrenches Used to turn nuts or hold the pieces of stock when tightening screws,nuts,and bolts
1.Adjustable wrench (a). Adjustable End Wrench It is handy and can quickly be adjusted for size to grip/grasp piece of stock (b). Vise-Grip Wrench A special wrench, which can be locked on to an object and will grip it with great pressure. The round knurled knob in the end of the handle is screwed in or out to adjust the jaws to the size of the object, which is to be gripped (c). Pipe wrench They are designed for tightening and loosening pipes as well as for holding round objects
2.Open-end wrench This wrench grasps the nuts on only two of its flat side, and is subject to slipping under a heavy pull. 3.Socket wrench It is very convenient to use and in most instances is faster to turn or remove the object than compared to other wrenches 4. Box wrench It is an excellent tool as it grips the nuts on all sides. This reduces the chances of slipping with resultant damage to the nut and possible the hand.
5.Allen wrench The end tip is shaped hexagonally to fit the same shape of the screw to be tightened or loosened.
Bearing Puller Use to pulling gears, bearings, and bushings on the shaft of the motor or generator. Center Punch Used to marking metal parts so that they can be correctly re-assembled as well as for marking and centering on metal part to bore holes. Cold Chisel Used to cut thin metal as well as to remove little projections of metal on smooth metal surfaces Hacksaw Cuts heavy cable, pipe, and conduit.
Pipe Burning Reamer Used to deburr or remove rough edges from inside cut conduit. Pipe cutter Used to cut small size of pipes. it has three small round cutters made of hardened steel. The pipe cutter is slipped over the pipe where the cut is to be made; the cutter is then pressed against the pipe and rotated around to cut a groove until the pipe is cut. Pipe Vise Are especially designed to hold pipe or round stock.
Bench Vise Used to hold pieces of stocks for hand tool operation such as filling, cutting, bending, tapping, threading and reaming. All vises consist essentially of fixed jaw, movable jaw, screws and handle Pipe Threader Used to thread rigid conduit pipe at a variety of locations on the job site. Hickey Used to bend rigid conduit to a variety of locations on the job site Push-pull Tape Rule Useful for rapid layout in measurements. Should be as wide as possible for easy extension.
Tin Snip Used for cutting of thin sheets of metals Test light Is a pocket size tool used to test line wire or circuit if there is a current in it. File Is made out of carbon steel with brittle and sharp teeth, used to smoothen and remove rough surfaces or edges of metals. Files have different sizes and shapes of blade with wooden handle. It is manufactured in flat, half-round and round file. Soldering Gun. The contour shape of this tool is similar to a hand gun with hard copper wire as soldering tip. this is used to solder joints and terminal connections
ELECTRICAL TESTS AND MEASURING INSTRUMENTS Panel meter A meter that measures only one electrical quantity is called a panel meter. The meters may be either analog or digital 1.Analog meters Meters with moving pointers are called analog meters. 2.Digital Meters The meter movement is replaced by an electronic digital display.
What do meters measure • A meter is a measuring instrument. • Anammetermeasures current, • Avoltmetermeasures the potential difference (voltage) between two points, and • Anohmmetermeasures resistance. • Amultimetercombines these functions, and possibly some additional ones as well, into a single instrument. • Before going in to detail about multimeter, it is important to have a clear idea of how meters are connected into circuits. • Diagramsin Next Slides show a circuit before and after connecting an ammeter
Ammeter An ammeter is an instrument that measures electric current. Types • DC Ammeter • AC Ammeter • To measure current, the circuit must be broken to allow the ammeter to be connected in series. • Ammeters must have a LOW resistance . • All the current flowing in the circuit must pass through the ammeter.
Procedure in measuring current • Select the current function • Select a range that is greater than the expected current • Physically interrupt the circuit • Observing polarity, connect the ammeter between the points created by the interruption.
Clamp meter Clamp meter is an instrument for measuring of current flow in a circuit
Volt meter A voltmeter is an instrument that measures voltage Types of voltmeters • DC Volt meter • AC Volt meter • To measure potential difference (voltage), the circuit is not changed: the voltmeter is connected in parallel . • voltmeters must have a HIGH resistance . • The voltmeter is connected in parallel between the two points where the measurement is to be made.
Procedure in measuring voltage • Select the correct voltage function (AC or DC) for the type of voltage used in the circuit • Select a range that is greater than expected voltage • Determine the polarity of the voltage to be measured by looking at the schematic diagram or at the battery terminals (not for AC) • Connect the negative (black) lead of the multimeter to the negative end of the voltage to be measured. Connect the positive (red) lead of the meter to the positive end of voltage
Ohm meter It is an instrument that measure resistances. It is also used for checking the continuity of electrical circuits, coils of wires, heaters, etc. When measuring or testing with an ohmmeter, make sure the device to be tested is free from any source. i.e. no voltage across the device to be tested • To measure resistance, the component must be removed from the circuit altogether • Ohmmeters work by passing a small current through the component and measuring the voltage produced. • If we try this with the component connected into a circuit with a power supply, the most likely result is that the meter will be damaged.
Procedure for measuring resistances • Remove power from the circuit • Select an appropriate range in the ohms function • When using, short (touch) the test leads. • Test the ohm adjust control until the pointer reads to zero ohm • Connect or touch the test leads to the terminals of the device whose resistance is to be measured
Megohmmeter • It is an ohmmeter that can measure very high resistance • When cranked ,it generates a DC voltage. The DC voltage is applied to the terminals of the equipment being tested for about one minute to test the strength of insulation resistance Applications • Test the insulation strength of wires and cables • Measure the insulation resistance of wires • Measure the insulation resistance between wire to ground
Procedures in using a Megohmmeter In the following example of using the megohmmeter,the test is made at the point where power leaves a motor starter Establishing a good ground Before the test is actually begun, it is necessary to establish a good ground. This is done by connecting the black (negative) test lead to ground and then grounding the red (positive) lead at another point. cranking the meter then tests the ground connection. If the dial moves to zero, the ground is good. This proves that the black lead is left in position while the test is done. Note: When the megohmmeter is being cranked, care must be taken not to touch the test leads because of the danger of electrical shock.
The first step in using the meter is to test it to make sure that it is functioning correctly • The next step is to prepare the equipment by • De-energizing the component • Verifying the power to the component is OFF • Disconnecting the component from its circuit • Connect the red lead to the bundle of wires • Read the meter-Record this value • Set the range switch to the discharge position-The purpose of the discharge position is to discharge the voltage stored uo in the equipment from the test. Safety Precaution: Do not disconnect the meter before the equipment has been discharged. The voltage present before discharging creates an electrical shock hazard • Interpret the reading-to determine the quality of insulation
Multimeter • A multimeter or a multitester is an electronic measuring instrument that combines several functions in one unit. • The most basic instruments include an ammeter, voltmeter and ohmmeter. • Analog multimeters are sometimes referred to as "volt-ohm-meters", abbreviated VOM. • Digital multimeters are usually referred to as "digital-multi-meters", abbreviated DMM. • A multimeter can be a handheld device useful for basic fault finding and field service work or a bench instrument
Analogue Multimeter • An analogue meter moves a needle along a scale. Switched range analogue multimeters are very cheap. The meter movement is delicate and dropping the meter is likely to damage it. • Each type of meter has its advantages. Used as a voltmeter, a digital meter is usually better because its resistance is much higher, 1 M ohm or 10 M ohm , compared to 200 ohm for a analogue multimeter on a similar range. • On the other hand, it is easier to follow a slowly changing voltage by watching the needle on an analogue display. • Used as an ammeter, an analogue multimeter has a very low resistance and is very sensitive, with scales down to 50 µA. More expensive digital multimeters can equal or better than this performance. • Most modern multimeters are digital and traditional analogue types are destined to become obsolete.
Digital Multimeter • Digital meters give an output in numbers, usually on a liquid crystal display. • The central knob has lots of positions. • We must choose which one is appropriate for the measurement you want to make. • If the meter is switched to 20 V DC, for example, then 20 V is the maximum voltage which can be measured. • This is sometimes called 20 V fsd, where fsd is short for full scale deflection. • Sometimes, we will want to measure smaller voltages, and in this case, the 2 V or 200 mV ranges are used.