Biddle MG-25A-Series_UG 电路图.pdf

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1、 Part _ 12507 Rev. 0 INSTRUCTION MANUAL For MEGOMETERS MODEL MG-25A, 50A, 100A the other is through the GUARD terminal and provides a path that bypasses the megohmmeter. Therefore, the megohmmeter will measure only the leakage current of the item connected between the HIGH VOLTAGE output terminal an

2、d the RETURN terminal. When testing an item which may have isolated metallic components that provide an unwanted current path, connect these isolated components together and to the GUARD terminal. Several diagrams are shown on the following pages which illustrate typical connections and can be used

3、as a guide. Part _ 12507 Rev. 0 6 TYPICAL CONNECTION DIAGRAMS Part _ 12507 Rev. 0 7 Part _ 12507 Rev. 0 8 TYPICAL CONNECTION DIAGRAMS Part _ 12507 Rev. 0 9 OPERATING INSTRUCTIONS C A U T I O N 1. O B S E R V E A L L S A F E T Y P R E C A U T I O N S! 2. Initial set-up of controls CONTROL POSITION ON

4、/OFF switch OFF HV switch OFF Megohmmeter RANGE switch 2000 METERED/NON-METERED switch METERED OUTPUT CONTROL knob 0 (Full counterclockwise) 3. Connect a grounding cable from the SAFETY GROUND terminal of the test set to a good electrical ground. Be sure a secure connection is made at both ends. 4.

5、Insert one end of the high voltage output lead into the HIGH VOLTAGE terminal of the test set and connect the other end to the item to be tested. 5. Connect one end of a lead to the RETURN terminal and the other end to the item to be tested. 6. If it is desired to bypass stray current caused by para

6、llel conductive paths around the megohmmeter, connect a lead from the GUARD terminal to the path(s) to be bypassed. See GUARD CIRCUIT section of manual for further explanation on use of this circuit. 7. Plug input line cord into a suitable power source as indicated on the nameplate of the test set.

7、BE SURE TEST SET IS GROUNDED. IF A 2-PRONG ADAPTOR IS USED, BE SURE GROUND LED OF ADAPTOR IS CONNECTED TO EARTH GROUND. 8. Turn ON/OFF switch to ON. No warm-up time is necessary. 9. Turn HV switch to ON. 10. Rotate output control knob clockwise until the desired test voltage is indicated on the kilo

8、voltmeter. If no output is obtained when rotating the output control knob clockwise, return it fully counterclockwise until the zero-start interlock switch is heard to click. Then rotate clockwise to obtain desired test potential. Part _ 12507 Rev. 0 10 11. Resistance is now indicated on the megohmm

9、eter. If the megohmmeter reading is greater than the lowest readable point on the next range, change the MEGOHMMETER RANGE switch to the next higher multiplying factor. This increases the sensitivity of the megohmmeter circuit and may be repeated if the new reading is greater than the lowest readabl

10、e point of the next range, etc. 12. The resistance of the item under test is determined by multiplying the megohmmeter reading times the MEGOHMMETER RANGE and by the multiplying factor (bottom sale) of the kilovoltmeter. INSULATION RESISTANCE (MEGOHMS) = MEGOHMMETER READING X MEGOHMMETER RANGE X KIL

11、OVOLTMETER MULTIPLYING FACTOR. NOTE: If the desired test voltage is not at a cardinal point on the scale of the kilovoltmeter, the multiplying factor will have to be estimated. 13. Turn HV switch OFF. 14. Return output control knob to 0 (full counterclockwise). 15. Check to see that the kilovoltmete

12、r reads 0 (the capacitive component of the item under test will hold a charge, and may take a long time to discharge). 16. Use a hot stick and rubber gloves to ground the item under test before disconnecting. After a test has been performed, the ground should be left on the item which was tested for

13、 at least as long as the total time that high voltage was applied. This is to prevent a voltage buildup due to absorption currents. It is a good policy to leave a ground on any time the item is not undergoing a test or is not in service. Part _ 12507 Rev. 0 11 MAINTENANCE INSTRUCTIONS Multi-Volt tes

14、t sets are designed and built for field use by utilities, industrial plants, service organizations and government agencies. When reasonable care is taken in use and storage, this test set will provide ling, trouble-free operation. A superficial inspection is recommended approximately once a month, a

15、nd a complete inspection should be given approximately every six months. On a monthly basis, the test set should be examined for structural damage. Verify that the fastening screws are secure and inspect the input line cord, test leads and terminals. Clean the case and control panel, and carefully c

16、lean-off the terminals with a lintless cloth or paper towel. Operate the test set and critically observe the action of control and instruments. Replace any burned-out indicator lamps. In addition to the above, approximately every 6 months, the test set should be removed from its enclosure and an inspection made of the control and instrument panel for signs of corrosion, insulation damage, loose screws, dirt or other deterioration. Check the brush on the variable auto-transformer (output control) for wear.