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Summary of Contents for BT 301B
- Page 1 Handbook TESTER301B...
- Page 3 T his handbook is for use with the Tester 301 B, manufactured by Edgcumbe Instruments Ltd.
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Page 4: Table Of Contents
TESTER 301 B HANDBOOK - CONTENTS Introduction 1, 2 Main Features Battery Charging 5, 6 Initial Charging and Subsequent Use Operating Instructions 9-12 Faults less than 100 metres from Testing End 13, 14 Practice use of the Tester 301 B 15, 16 Accuracy and Interpretation 17, 18... - Page 5 Fig. 1 Tester 301 B Used for location of disconnection and short circuit faults in local networks. Range 2.5 km.
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Page 6: Introduction
INTRODUCTION The T ester 301 B uses Time Domain Reflectometry (pulse echo principle) to locate disconnection (DIS) and short circuit (S/C) faults in a local cable network. Electrical pulses are transmitted along the pair by the Tester 301 B and relfected back to the sending end by a fault on the pair. The reflected pulse is detected by the Tester 301 Band displayed on a cathode ray tube (C.R.T.) screen. - Page 7 TESTER 3018 LI N E , / I I BATTERY STATE INDICATOR l·SkVOC GENERATED INTERNALLY GAI N CURSOR E X T ON REMOVAL OF PANEL BY AUTHORISED PERSONNEL ONLY OFF/ 'v--jl\ DI S FAULT -..+ � ©...
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Page 8: Main Features
MAIN FEATURES Fig. 2 shows the front panel of the Tester 301 B. The following points should be noted. The pair under test is connected to the Tester 301 Bline terminals via the test leads provided. ( b) T he supply select switch has three positions OFF/CHARGE (ii) (iii) - Page 9 Fig. 3. Rectifier 162A Fig. 4. Rectifier 161 A...
- Page 10 BATIERY CHARGING NORMAL CHARGING Keep your Tester 301 B battery fully charged; always switch the tester off when not in use and keep it connected to a vehicle charging point (Rectifier 162A) . Correct connection to the Tester 301 Bis indicated red lights on the Tester 301 B and the Rectifier 162A.
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Page 11: Initial Charging And Subsequent Use
INITIAL CHARGING AND SUBSEQUENT USE Before the Tester B is used for the first time the battery must be given a full charge using a mains powered charging unit (Rectifier A which is held at the T.E.C. - see fig. The battery should be charged for at least hours, care being taken to see that the selector switch is in the... - Page 12 To check the test lead short the ends together. The display should alter. If this does not occur replace the test lead. 4. 5 If the above tests are performed satisfactorily the instrument can be assumed to be in working order and should be switched off and connected to a vehicle charging point (Rectifier 162A-see fig.
- Page 13 TRANSMITTED PULSE BREAKPOINT LINE CURSOR FAULT LINE CURSOR BREAKPOINT Fig.5 Flg.6 Fig. Radio Frequency Interference Disconnection or Open Circuit Fault Short Circuit Fault...
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Page 14: Operating Instructions
OPERATING INSTRUCTIONS For your own safety, check that there are no hazardous voltages on the cable pair to be tested. Safety is no accident. Connect the pair under test to the line terminals using the test leads provided. Set the gain and cursor control to the minimum settings (anti-clockwise). Set the R. F. control to the centre position. - Page 16 Adjust the cursor control until the line cursor coincides with the break point of the fault pulse (see fig. The distance to the fault (in kilometres) may now be read directly from the liquid crystal display (see fig. and fig. If the fault is closer than 100 metres from the testing point, the fault pulse will be indistinguishable from the transmitted pulse as shown in fig.
- Page 17 PARTIAL FAULTS FAULT PULSE? LINE CURSOR BREAKPOIN T LINE CURSOR Fig.10 Flg.11 Fault pulse clearly visible Fault pulse hidden by after either connecting approx. transmitted pulse 100m of jumper wire or installing ARTIFICIAL the artificial line between the LINE Tester 301 Band the pair under test.
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Page 18: Faults Less Than 100 Metres From Testing End
FAULTS L ESS THAN 100 METRES FROM TESTING END The procedure to be followed is the same as in section 5, but because of the short distance to the fault, the fault pulse may not be distinguishable from the transmit pulse, as shown in Fig. 10. To overcome this difficulty either install a length of jumper wire measuring 100 metres or the artificial line between the line terminals and the pair under test. - Page 19 TRANSMITTED PULSE FAULT BREAKPOINT LINE CURSOR FAULT LINE CURSOR BREAKPOINT LINE CURSOR BREAKPOINT Fig.3 Fig.14 Fig.15 Fig.13 Short Circuit Fault Correct Measurement Disconnection or Open Circuit...
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Page 20: Practice Use Of The Tester 301 B
PRACTICE USE OF THE TESTER 3018 Obtain a reel of jumper wire (length marked) with access to both ends, connect the T ester 301 B to one end and leave the other end open circuit. Turn the supply switch to ON, adjust the tester to measure the length of the jumper wire (using the and note this length. - Page 21 FAl1tfS I �LL SAY ff/£ tOWJV' li£Rc.I...
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Page 22: Accuracy And Interpretation
ACCURACY AND INTERPRETATION The accuracy obtainable with the T ester B is dependent on:- ( a ) The accuracy of the instrument itself. ( b ) The condition and characteristics of the pair under test. Water in a cable may alter its transmission characteristics and thus give an incorrect reading. Also the measured length and actual overground cable length may differ due to the lay of the cable pairs. -
Page 23: Servicing
SERVICING Before sending the Tester 301 B for servicing ensure that the printed circuit board mounted fuses have not ruptured and the batteries are not faulty. Note:- Checking and replacement of batteries and printed circuit board mounted fuses is to be carried out by authorised personnel only. - Page 27 For Advice Contact:- NPA 1.7 ALBAN PARK2 UNIT1 ST.ALBANS AL4 OJJ...
- Page 28 NOTE:- THIS BOOKLET IS NOT TO BE REPRODUCED WITHOUT THE PRIOR CONSENT OF Printed by: Edgcumbe Instruments Ltd F301B/8 ISSUE 5...
- Page 30 EDGCUMBE INSTRUMENTS LTD.