1. ADT490 Panel Theory

2. 2 System Power Supply Grounding ‣ Circuit separates positive / negative from Ground ‣ Ground fault - resistance to ground ≤ 10 kΩ ‣ System power supply ‣ Line - black ‣ Neutral - white (return) ‣ Ground - green ‣ Exterior components bonded to Ground

3. 3 Power Supply ‣ Output 27 to 30 Vdc 3

4. 4 Power Supply Fault Analysis ‣ Power on - how do we know? ‣ Disconnect or breaker station - looking for? 4

5. 5 Power Supply Checklist 5

6. 6 Power Supply Checklist 2 6

7. 7 Battery Charger Concepts ‣ 2 x 12 V or 4 x 6 V batteries ‣ To charge requires 27.4 to 28 V ‣ must be recharged to 70% within 12 hours (ULC) ‣ 5 to 35 mA - float Charge ‣ Fast Charge - larger ‣ Battery Condition Monitor ‣ Ammeter in Series to check the Charge rate (A) ‣ Can check power supply with DC & AC Voltage Measurements 7

8. 8 Battery Charger Concepts 8

9. 9 Electrical Supervision ‣ small current though an EOL Resistor ‣ no current though an EOL Capacitor ‣ Power resistors ‣ approximately 200 Ω ‣ 1 volt each ‣ about 2 W 9

10. 10 Electrical Supervision 10

11. 11 Detection - Open Circuit 11

12. 12 EOL Resistor Function ‣ Limits current through wiring ‣ Regulates the voltage in the circuit 12

13. 13 EOL Capacitor Function ‣ Siemens System 3 or MXL ‣ EOL Capacitor ‣ Blocks DC ‣ Smooths ripple voltage 13

14. 14 Detection Circuit with EOL Capacitor 14

15. 15 EOL Capacitor Waveform 15

16. 16 EOL Capacitor Waveform 16

17. 17 Locating Faults ‣ Voltage on open EOL Capacitor circuit is 20.5V (System 3) & 21.5V (MXL) ‣ Voltage before the break ‣ 0 V after the break 17

18. 18 EOL Relays ‣ Mostly used on security systems or ‣ 4 wire devices 18

19. 19 EOL Relays 19

20. 20 Wiring Architectures ‣ Class B ‣ Class A ‣ Split Class B ‣ Tee-Tapped 20

21. 21 Class B Wiring - Placement or Location Supervised (87%) 21

22. 22 Class A Wiring - Placement or Location Supervised (8%) 22

23. 23 Class A Wiring - Greater Reliability 23

24. 24 Class B Wiring with Tee-Taps ‣ Tap is unsupervised ‣ Reason each device is checked for open - S537 ‣ Some vendor use twice EOL size for main run and single tap 24

25. 25 Class B Wiring with Tee-Taps 25

26. 26 Addressable Loop - no EOL ‣ A fault cannot disable more than 1 Zone 26

27. 27 Signal Circuit Supervision ‣ Terminal may indicate polarity in alarm - not always ‣ 24 VDC can be as low as a few volts ‣ Shorts causes a circuit Trouble 27

28. 28 Signal Circuit Alarm Operation ‣ Device could be reverses - rings supervision not alarm ‣ Don’t exceed 85% of Current - Why? 28

29. 29 Class A Signal Circuits ‣ Class A good for opens ‣ Not good for shorts - Why? 29

30. 30 Speaker Circuits - Supervision 30

31. 31 Speaker Circuits - Alarm 31

32. 32 Speaker Circuits - Alarm ‣ 25 Vrms 20 and 40 mA for speaker + 5 mA for EOL ‣ 70.7 Vrms 7.1 and 14.1 mA for speaker + 7.1 mA for EOL (equivalent to 1/2 W Speaker) 32

33. 33 Split Speaker Circuits 33

34. 34 Split Speaker Circuits 34

35. 35 Telephone Circuits 35

36. 36 Improperly Connected Signals 36

37. 37 end of Presentation