TRAFFIC CONTROL TELEPHONE SYSTEMS Circuit - Sam Hallas
TRAFFIC CONTROL TELEPHONE SYSTEMS Circuit - Sam Hallas
TRAFFIC CONTROL TELEPHONE SYSTEMS Circuit - Sam Hallas
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Operate CVK, note meter reading on the 70-volt scale, and if necessary<br />
operate range key so that reading is near 25 volts.<br />
Note this reading, and check the test battery voltage by operating SCK.<br />
The resistance multiplied by 1, 10 or 100 can then be determined from the<br />
appropriate curve on the chart, or by interpolating between curves (Fig.<br />
22).<br />
Resistance by Voltmeter Test<br />
Fig. 21.<br />
7. Line Resistance Measurements by Voltmeter Method. (See Fig. 21.)<br />
If the resistance to be measured is fluctuating (line leakage in wet<br />
weather for instance), if may be difficult to obtain a balance on the<br />
Wheatstone Bridge, and a voltmeter test, which will show the fluctuations,<br />
may be preferred.<br />
To measure the Line Loop Resistance. Insert test plugs into the line to<br />
be tested then proceed as in paragraphs 6 or 7.<br />
8. Line to Earth Measurement by Voltmeter Method. (See Fig. 21.)<br />
Insert plugs into line to be tested. Operate CVK and EAK for measuring<br />
"A" line to earth, or EBK for measuring "B" line to earth, and proceed<br />
as in paragraph 6 except that the test battery voltage should be checked<br />
before the earth test keys are operated.<br />
9. Measurement of Incoming Volts from Line.<br />
Insert test plugs into appropriate line, operate LVK, CVK and RAK,<br />
read voltage on the 70-volt scale of meter. N.B.— If CVK is operated<br />
without LVK, the 50-volt test battery will be connected in series with the<br />
incoming voltage.<br />
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