Guide to the Practical Elements of Electrical Testing |
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Page 59
... discharge rate , would impress one as being eminently suitable , but they require constant attention and perfect insulation , the former being a matter which involves time and labour , and the latter a condition not easily obtainable in ...
... discharge rate , would impress one as being eminently suitable , but they require constant attention and perfect insulation , the former being a matter which involves time and labour , and the latter a condition not easily obtainable in ...
Page 64
... Discharge Key . - A key which performs a similar office to the above is illustrated below , and is known as Webb's condenser discharge key . A ( Fig . 28 ) is a solid brass lever of rectangular section , pivotted at a , and normally ...
... Discharge Key . - A key which performs a similar office to the above is illustrated below , and is known as Webb's condenser discharge key . A ( Fig . 28 ) is a solid brass lever of rectangular section , pivotted at a , and normally ...
Page 83
... discharge the cab'e thoroughly between the respective applications of the current . A further check is provided by what are known as " earth readings . " If we disconnect the battery from the cable at the end of , say , five minutes ...
... discharge the cab'e thoroughly between the respective applications of the current . A further check is provided by what are known as " earth readings . " If we disconnect the battery from the cable at the end of , say , five minutes ...
Page 84
... discharge , as otherwise , when Kl is again depressed , the battery E will be short- circuited . Now as regards the question of efficient earths . In testing a circuit which has been already wired , we have , of course , to depend upon ...
... discharge , as otherwise , when Kl is again depressed , the battery E will be short- circuited . Now as regards the question of efficient earths . In testing a circuit which has been already wired , we have , of course , to depend upon ...
Page 95
... discharge of some 10 am- pères , and an adjustable resistance , R , which is mani- pulated until the above current , or its approximate value , as indicated on an ammeter connected in circuit , but not shown in the diagram , is flowing ...
... discharge of some 10 am- pères , and an adjustable resistance , R , which is mani- pulated until the above current , or its approximate value , as indicated on an ammeter connected in circuit , but not shown in the diagram , is flowing ...
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Common terms and phrases
adjustable arm alternating current ammeter ampère apparatus cable under test calibration capacity charging circuit key Clark Cell Co-eff coil conductor connected consists constant constructed copper D'Arsonval D'Arsonval Galvanometer Daniell cell deflection method deflection results depressed described discharge disconnected drum earth ebonite electrode electromotive force Elliott Bros extremity fault galvano glass high resistance immersed indicated in Fig instrument insulation resistance known latter leakage length lever localisation loop low resistance magnetic megohms mercurous sulphate mercury meter metre bridge millimetre mounted Nalder Bros nected needle noted Ohm's law ohms ordinary platinum plugs pole practical reading reflecting galvanometer represented in Fig resistance measurement respectively scale short circuit shown shunt sistance slide wire slider standard cell standard resistance suitable surface suspended switch temperature terminals testing battery tion total resistance tube usually vanometer voltage voltmeter volts Wheatstone bridge whilst zero zinc sulphate
Popular passages
Page 40 - ... above the cork, using sufficient to cover completely the zinc and soldering. The glass tube containing the platinum wire should project some way above the top of the marine glue. The cell may be sealed in a more permanent manner by coating the marine glue, when it is set, with a solution of sodium silicate, and leaving it to harden.
Page 50 - As a unit of resistance, the international ohm, which is based upon the ohm equal to 10" units of resistance of the CGS system of electromagnetic units, and is represented by the resistance offered to an unvarying electric current by a column of mercury at the temperature of melting ice, 14.4521 grams in mass, of a constant cross-sectional area and of the length of 106.3 centimetres.
Page 39 - Sulphate. — Take mercurous sulphate, purchased as pure, mix with it a small quantity of pure mercury, and wash the whole thoroughly with cold distilled water by agitation in a bottle; drain off the water, and repeat the process at least twice. After the last washing, drain off as much of the water as possible.
Page 40 - Then insert the cork and zinc rod, passing the glass tube through the hole prepared for it. Push the cork gently down until its lower surface is nearly in contact with the liquid. The air will thus be nearly all expelled, and the cell should be left in this condition for at least...
Page 39 - ... any free acid. The crystals should be dissolved with the aid of gentle heat, but the temperature to which the solution is raised should not exceed 30
Page 40 - ... which the zinc rod can pass tightly ; at the other side bore another hole for the glass tube which covers the platinum wire; at the edge of the cork cut a nick through' which the air can pass when the cork is pushed into the tube.
Page 39 - C. Keep the paste for an hour at this temperature, agitating it from time to time, then allow it to cool ; continue to shake it occasionally while it is cooling. Crystals of zinc sulphate should then be distinctly visible, and should be distributed throughout the mass ; if this is not the case, add more crystals from the stock bottle, and repeat the whole process. This method ensures the formation of a saturated solution of zinc and mercurous sulphates in water. To set up the Cell. The cell may conveniently...
Page 38 - ... carefully removing any loose pieces of the zinc. Just before making up the cell, dip the zinc into dilute sulphuric acid, wash with distilled water, and dry with a clean cloth or filter paper.
Page 40 - ... the glass tube which covers the platinum wire ; at the edge of the cork cut a nick through which the air can pass when the cork is pushed into the tube. Wash the cork thoroughly with warm water, and leave it to soak in water for some hours before use.