1. Surge Protection Devices
By: Stelios Ioannou
George Bolos

2. Definition of Power Quality
Power Quality is measured at end-user side.
Good power quality: any electrical device at the end-user side performs as expected and intended.
Poor power quality: If any electrical device misbehaves as a result of fluctuations in voltage waveform magnitude, frequency, harmonic distortion, symmetry, or even discontinuity in supply, then power quality is said to be “poor”.

3. Main Power Quality Problems
Voltage Sags
Micro-Interruptions
Long Interruptions
Voltage Spikes
Voltage Swells
Voltage Unbalance
Harmonic Distortion

4. Power Quality Problems Facts
88.5% of PQ Problems are Caused due to Transients.
Source: REO, Power Quality Facts. Online Posting: March 21, 2005.

5. According to EPRI (Electric Power Research Institute):
In 1999 power sags, surges and transients cost US industry over $50B in downtime.
In 2000 the figure doubled to over $100B.
In 2001 related downtime doubled again to $200B.
By comparison, the 2 day NE USA blackout of 2003 is estimated to cost the US economy $17B.

6. Transients and AC Power
Power line transient voltage levels can be in excess of 10kV approximately compared with an office block in town which can expect levels of 3kV.

7. IEEE Definitions of Transients (Std.4-1995)
Open-Circuit Voltage Waveform:
- Front Time: 1.2uS ± 0.36uS
Decay Time (Duration): 50uS ± 10uS
Short-Circuit Current Waveform:
- Front Time: 8uS (+1uS, -2.5uS)
- Duration: 20uS (+8uS, -4uS)

8. Transients Impact On Devices
Impact to Electronic Loads
Circuit Board Failure
Yes
-----
Data Transmit Errors
Memory Scramble
Hard Disk Crash
SCR Failure
Process Interrupt
Power Supply Failure
Program Lock Up
Source: Dranetz handbook of Power Quality.

9. Surge Protection Devices
surge arresters, transient voltage surge suppressors (TVSS)
Surge Diverters
Surge Suppressors

10. Technology Profiles
Surge Suppression
Surge Diversion

11. Surge Suppression Profile
Source: Zero Surge Inc., “Surge Removal Filters”. Online Posting: March 21, 2005.

12. Surge Suppression Waveforms
Attenuated Output.
Source: Zero Surge Inc., “Surge Removal Filters”. Online Posting: March 21, 2005.

13. Ideal V-I Clamping Characteristics.
Surge Diverters
Ideal V-I Clamping Characteristics.

14. Surge Diverters Devices and Applications
Zener Diodes: Ideal clamping characteristics but poor energy limitations.
Crowbars: High energy capabilities, but power follow problem.
Metal Oxide Varistors (MOV): low stand-by currents, high short-circuit current capabilities (α diameter) , wide range of operating voltage (α to thickness), energy is evenly distributed on the volume of the MOV.

15. Surge Diverter Waveforms
MOV Clamps a 1000V Transient Voltage to 400V and a Current of 344A.

16. Common Question
Q: 400 volts let-through voltage, wouldn’t that damage an electronic device operating at 120V????? A:
400 volts is peak value, whereas 120VRMS (170V peak).
The duration of the let-through voltage is less than 100 us.

17. CBEBA Curve
167 us

18. Comparison Surge Diverters Ground Contamination.
MOV is sacrificial element.
Surge Suppressors
Attenuation of Data.

19. Surge Protection Devices Classification And Certification
Performance
Reliability
Mode of Suppression
Underwriters Laboratories Inc. (

20. Performance
Class 1 products have suppressed voltage ratings of 330 volts. Under specified test conditions, at any transient voltage level, their measured suppressed voltages are 330 volts or less.
Class 2 products have suppressed voltage ratings of 400 volts.
Class 3 products have ratings of 500 volts.

21. Reliability
Grade A products must be certified to have passed 1000 surges of 6000 volts and 3000 amperes without failure.
Grade B products must pass 1000 surges of 4000 volts and 2000 amperes.
Grade C products must pass 1000 surges of 2000 volts and 1000 amperes.

22. Mode of Suppression
Mode 1 products protect the ground by not diverting surge energy to it.
Mode 2 products contaminate the ground wire.

23. Price Range Surge suppressors (Class A, Grade 1, Mode 1): 7.5A: $125
Surge Diverters (Only Performance Data is available):
Class A: approximately $30
Class D: approximately $9.99