Download Transient Voltage Surge Suppression Design

Transient Voltage Surge Suppression
Design and Correlation
Marcus O Durham, PhD, PE
THEWAY Corp
Tulsa, OK
Karen D Durham, EIT
NATCO
Tulsa, OK
Robert A Durham, PE
RADCo Consulting
Broken Arrow, OK
Introduction
• Most protection consists of traditional
arresters
• Most devices remain un-validated for app
• Cost of inadequate protection
– Equipment failure
– Downtime – lost revenue
• Proper protection improves bottom line
Introduction
•
•
•
•
Components and systems tested
Custom designs evaluated
Design approaches discussed
Cost vs. protection evaluated
ANSI Standard Tests
• Tests conducted according to ANSI C62.1
procedures
• Open circuit (voltage) evaluated using
1.2/50 wave shape
• Short circuit (current) evaluated using
8/20 wave shape
ANSI C62.1 Waveforms
1000
500
800
400
100
200
0
0
-100
0
10
20
30
-200
40
1.2 / 50 wave-shape
500
500
400
400
300
300
200
200
100
100
0
0
-100
-100
-10
0
10
20
30
8 / 20 wave-shape
-200
40
Amps
-200
-10
Volts
Volts
200
400
Amps
300
600
Protection Devices
• Chosen based on
system conditions
–
–
–
–
• Only a few types
available
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–
–
–
Voltage
Frequency
Exposure
Grounding
Physical Separation
Ceramic Materials
Passive Devices
Solid State Components
V
I
Shunt current
F
Filter frequencies
Clamp voltage
E
Block energy
Protection Devices
Observations
• Test signal - impulse
Power systems - RMS
• Vpeak = 2 * VRMS
• Most devices do not
operate until 2*Vrated
500
500
400
400
300
300
200
• Let-through voltage
often 22 * Vrated
200
100
100
0
0
-100
-200
-100
-10
0
10
20
30
120V Gas Tube Response
40
Passive Elements
Capacitors
•
•
•
•
Shunt voltage to ground
Store Energy
Size  Dissipation
Hold elevated
voltage on line
500
500
400
400
300
300
200
200
100
100
0
0
-100
-100
-200
-10
0
10
20
30
Capacitor Response
40
Passive Elements
Inline Devices
•
•
•
•
•
Resistance is consideration
4-20 ma loop compliance = 600 max
Must be small enough to not impact ops
Must be large enough to limit current
Must have large enough power rating
Passive Elements
Inductors
• Block current changes
• Size  Voltage buildup
• Induce higher V
due to I changes
V = L di/dt
• Air core preferred
1000
500
400
800
300
600
200
400
100
200
0
0
-100
-200
-200
-10
0
10
20
30
Inductor Response
40
Filters
•
•
•
•
Made of inline inductor and shunt capacitor
Must pass 60 Hz for power system
Transients look like 1MHz signal
Resonance will occur
at some point
• Filters not generally
recommended
1000
500
400
800
300
600
200
400
100
200
0
0
-100
-200
-200
-10
0
10
20
30
Filter Response
40
Semiconductors
•
•
•
•
Fast, handle less energy
MOV = Zinc Oxide = Voltage
I = kV
SiC  = 10
ZnO  = 25 - 60
• Hi W = Hi C
 Hi Z @ Hi f
500
500
400
400
300
300
200
200
100
100
0
0
-100
-100
-200
-10
0
10
20
30
Semiconductor Response
40
Semiconductors
•
•
•
•
Diodes fastest, but have low power rating
Couple with gas tube to increase rating
MOVs have highest power rating
Still must be coupled with secondary device
MOV
Grounds
• Uniform equi-potential ground is most effective
protection
• Generally, single point connection
• Isolated @ source for hi energy
• Isolated @ load for remote instrumentation
Instrumentation TVSS
•
•
•
•
Most common are inline devices
Problem with Z and f response
Commercial use common mode
Problem with remote app (circulating I)
xmitter
+
_
+
_
s
xmitter
+
_
s
Isolated Signal
Ground
+
_
Remote Instrumentation TVSS
• Isolate transmitter and DCS
• Use differential mode MOVs
• Use inline inductors for isolation
• Inductors round the curve
• Dissipates energy
w/o ground
500
500
400
400
300
300
200
200
100
100
0
0
-100
-100
-200
-10
0
10
20
30
40
Remote TVSS Response
Power TVSS
• Shunt type adequate
• Inline devices
– Failed or
– Ineffective in performance or packaging
– Most had more output V than input V
• Hard to match f response and low Z
• Often L-N adequate, while L-G worsened
Power TVSS Response
500
500
400
400
300
300
200
200
100
100
0
0
-100
-100
-200
-10
0
10
20
30
1000
500
40
400
800
L-N Response
300
600
200
400
100
200
0
0
-100
-200
-200
-10
0
10
20
30
L-G Response
40
Power TVSS
• Highly sophisticated design
–
–
–
–
MOV, Gas tube and capacitor L-N @ input
Fe core inductor inline
MOVs L-N, L-G, N-G @ output
Transorb L-N @ output
• Output V slightly higher than other MOVs
• Handles more energy
• Ringing less due to transorb
Motor TVSS
480 Volt
•
•
•
•
Complete system with filters
6000 V L-N & G input  5900V pass-through
Grounds shorted  ringing on output
R load  harmonic spikes every 10 S
• MOVs as effective
• Primary arresters enhance MOV response
TVSS Challenges
• Follow-through
– Gas tube
– MOVs
– Diodes



• Degradation
–
Select device w/ lifetime hit rating>100,000
• Catastrophic failure
– Shorted @ life or overpowered
– Open with very excessive power (melts)
Conclusions - General
• The engineer with information is never at the
mercy of opinions.
• Proper application of protection should be based
on tested performance
• Response to standard waveforms can be used to
determine circuits of proprietary units
Test
Device
1Open Circuit
2Open Circuit
3Short Circuit
Rating Units
Test Peak Min V Peak Min I Peak V
Voltage V
I
Out
1000 1011
8
11
4
1000 1009
3
13
-6
1000
99
-4 458 -31
Conclusions - Components
• Most devices do not provide substantial
protection until 200% rated voltage
• Inductors can create Vout >> Vin
• Filters resonate at some transient frequency
• Higher energy devices tend to be slower
• Semiconductor devices need primary arrester to
handle hi energy
Conclusions - TVSS
• Remote systems should dissipate energy without
ground
• Power inline devices failed or did not provide
proper protection
• More sophisticated circuits did not provide
additional protection
• Most effective protection is proper grounding
system
Questions ?