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How can I compare a TVS diode with a varistor?
Clash Royale CLAN TAG#URR8PPP
up vote
2
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For a 120Vac line protection element, comparing this TVS diode:
With this varistor:
The immediate differences I see are:
- The varistor is marginally cheaper
- The varistor specifies a maximum working voltage much, much smaller than its clamp voltage. There seems to be no maximum working voltage on the diode, only the breakdown voltage.
- The diode is well-specified, and includes many graphs of its I/V characteristics. The varistor only has one graph, of clamp voltage against surge current.
In a simple application of a parallel AC line protection element, why would I choose a varistor over a bidirectional TVS diode?
diodes protection zener tvs varistor
asked 39 mins ago
Reinderien
718313
add a comment |Â
up vote
2
down vote
favorite
For a 120Vac line protection element, comparing this TVS diode:
With this varistor:
The immediate differences I see are:
- The varistor is marginally cheaper
- The varistor specifies a maximum working voltage much, much smaller than its clamp voltage. There seems to be no maximum working voltage on the diode, only the breakdown voltage.
- The diode is well-specified, and includes many graphs of its I/V characteristics. The varistor only has one graph, of clamp voltage against surge current.
In a simple application of a parallel AC line protection element, why would I choose a varistor over a bidirectional TVS diode?
diodes protection zener tvs varistor
asked 39 mins ago
Reinderien
718313
2
Consult UL here, but I seem to recall silicon TVS devices are not permitted for mains protection across the board.
– Matt Young
29 mins ago
add a comment |Â
up vote
2
down vote
favorite
up vote
2
down vote
favorite
For a 120Vac line protection element, comparing this TVS diode:
With this varistor:
The immediate differences I see are:
- The varistor is marginally cheaper
- The varistor specifies a maximum working voltage much, much smaller than its clamp voltage. There seems to be no maximum working voltage on the diode, only the breakdown voltage.
- The diode is well-specified, and includes many graphs of its I/V characteristics. The varistor only has one graph, of clamp voltage against surge current.
In a simple application of a parallel AC line protection element, why would I choose a varistor over a bidirectional TVS diode?
diodes protection zener tvs varistor
asked 39 mins ago
Reinderien
718313
For a 120Vac line protection element, comparing this TVS diode:
With this varistor:
The immediate differences I see are:
- The varistor is marginally cheaper
- The varistor specifies a maximum working voltage much, much smaller than its clamp voltage. There seems to be no maximum working voltage on the diode, only the breakdown voltage.
- The diode is well-specified, and includes many graphs of its I/V characteristics. The varistor only has one graph, of clamp voltage against surge current.
In a simple application of a parallel AC line protection element, why would I choose a varistor over a bidirectional TVS diode?
diodes protection zener tvs varistor
diodes protection zener tvs varistor
asked 39 mins ago
Reinderien
718313
asked 39 mins ago
Reinderien
718313
asked 39 mins ago
Reinderien
718313
asked 39 mins ago
Reinderien
718313
asked 39 mins ago
Reinderien
718313
718313
2
Consult UL here, but I seem to recall silicon TVS devices are not permitted for mains protection across the board.
– Matt Young
29 mins ago
add a comment |Â
2
Consult UL here, but I seem to recall silicon TVS devices are not permitted for mains protection across the board.
– Matt Young
29 mins ago
2
2
Consult UL here, but I seem to recall silicon TVS devices are not permitted for mains protection across the board.
– Matt Young
29 mins ago
Consult UL here, but I seem to recall silicon TVS devices are not permitted for mains protection across the board.
– Matt Young
29 mins ago
add a comment |Â
2 Answers
2
active
oldest
votes
up vote
3
down vote
The most obvious difference is the Pmax power rating for heat dissipation.
5 watts MOV vs 0.25 watts TVS
Peak current MOV is better for high AC line surges for locations with unbalanced lines so 100A half wave at 60Hz Where one phase might have a short resulting in the other phase possible have a half cycle over voltage , this then ought to blow a designed in fuse.
TVS is better for lightning surges 20us so 1500A. THis may also need a fuse but can be reduced with a line filter.
answered 26 mins ago
Tony EE rocketscientist
59.1k22088
add a comment |Â
up vote
2
down vote
Varistors are "baked" semiconductors, their properties aren't tightly controlable. Think of them as a mesh of billions of PN junctions. Their big pro is they can both short a spike and turn it into heat smoothly because of the high mass of the actual mesh.
In addition, as the varistor heats up, it gets more conducting and this can be used to blow a fuse for the case the overvoltage is not transient but steady. When the overvoltage is gone, the user replaces the fuse and the device can be used again.
You cannot do this with a TVS as it would blow before a fuse could react. You had to limit the current through it some way. Usually, this means you are using a TVS only on signal lines where the current is limited by the existing circuit itself.
answered 9 mins ago
Janka
7,1921718
add a comment |Â
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
3
down vote
The most obvious difference is the Pmax power rating for heat dissipation.
5 watts MOV vs 0.25 watts TVS
Peak current MOV is better for high AC line surges for locations with unbalanced lines so 100A half wave at 60Hz Where one phase might have a short resulting in the other phase possible have a half cycle over voltage , this then ought to blow a designed in fuse.
TVS is better for lightning surges 20us so 1500A. THis may also need a fuse but can be reduced with a line filter.
answered 26 mins ago
Tony EE rocketscientist
59.1k22088
add a comment |Â
up vote
3
down vote
The most obvious difference is the Pmax power rating for heat dissipation.
5 watts MOV vs 0.25 watts TVS
Peak current MOV is better for high AC line surges for locations with unbalanced lines so 100A half wave at 60Hz Where one phase might have a short resulting in the other phase possible have a half cycle over voltage , this then ought to blow a designed in fuse.
TVS is better for lightning surges 20us so 1500A. THis may also need a fuse but can be reduced with a line filter.
answered 26 mins ago
Tony EE rocketscientist
59.1k22088
add a comment |Â
up vote
3
down vote
up vote
3
down vote
The most obvious difference is the Pmax power rating for heat dissipation.
5 watts MOV vs 0.25 watts TVS
Peak current MOV is better for high AC line surges for locations with unbalanced lines so 100A half wave at 60Hz Where one phase might have a short resulting in the other phase possible have a half cycle over voltage , this then ought to blow a designed in fuse.
TVS is better for lightning surges 20us so 1500A. THis may also need a fuse but can be reduced with a line filter.
answered 26 mins ago
Tony EE rocketscientist
59.1k22088
The most obvious difference is the Pmax power rating for heat dissipation.
5 watts MOV vs 0.25 watts TVS
Peak current MOV is better for high AC line surges for locations with unbalanced lines so 100A half wave at 60Hz Where one phase might have a short resulting in the other phase possible have a half cycle over voltage , this then ought to blow a designed in fuse.
TVS is better for lightning surges 20us so 1500A. THis may also need a fuse but can be reduced with a line filter.
answered 26 mins ago
Tony EE rocketscientist
59.1k22088
answered 26 mins ago
Tony EE rocketscientist
59.1k22088
answered 26 mins ago
Tony EE rocketscientist
59.1k22088
answered 26 mins ago
Tony EE rocketscientist
59.1k22088
59.1k22088
add a comment |Â
add a comment |Â
up vote
2
down vote
Varistors are "baked" semiconductors, their properties aren't tightly controlable. Think of them as a mesh of billions of PN junctions. Their big pro is they can both short a spike and turn it into heat smoothly because of the high mass of the actual mesh.
In addition, as the varistor heats up, it gets more conducting and this can be used to blow a fuse for the case the overvoltage is not transient but steady. When the overvoltage is gone, the user replaces the fuse and the device can be used again.
You cannot do this with a TVS as it would blow before a fuse could react. You had to limit the current through it some way. Usually, this means you are using a TVS only on signal lines where the current is limited by the existing circuit itself.
answered 9 mins ago
Janka
7,1921718
add a comment |Â
up vote
2
down vote
Varistors are "baked" semiconductors, their properties aren't tightly controlable. Think of them as a mesh of billions of PN junctions. Their big pro is they can both short a spike and turn it into heat smoothly because of the high mass of the actual mesh.
In addition, as the varistor heats up, it gets more conducting and this can be used to blow a fuse for the case the overvoltage is not transient but steady. When the overvoltage is gone, the user replaces the fuse and the device can be used again.
You cannot do this with a TVS as it would blow before a fuse could react. You had to limit the current through it some way. Usually, this means you are using a TVS only on signal lines where the current is limited by the existing circuit itself.
answered 9 mins ago
Janka
7,1921718
add a comment |Â
up vote
2
down vote
up vote
2
down vote
Varistors are "baked" semiconductors, their properties aren't tightly controlable. Think of them as a mesh of billions of PN junctions. Their big pro is they can both short a spike and turn it into heat smoothly because of the high mass of the actual mesh.
In addition, as the varistor heats up, it gets more conducting and this can be used to blow a fuse for the case the overvoltage is not transient but steady. When the overvoltage is gone, the user replaces the fuse and the device can be used again.
You cannot do this with a TVS as it would blow before a fuse could react. You had to limit the current through it some way. Usually, this means you are using a TVS only on signal lines where the current is limited by the existing circuit itself.
answered 9 mins ago
Janka
7,1921718
Varistors are "baked" semiconductors, their properties aren't tightly controlable. Think of them as a mesh of billions of PN junctions. Their big pro is they can both short a spike and turn it into heat smoothly because of the high mass of the actual mesh.
In addition, as the varistor heats up, it gets more conducting and this can be used to blow a fuse for the case the overvoltage is not transient but steady. When the overvoltage is gone, the user replaces the fuse and the device can be used again.
You cannot do this with a TVS as it would blow before a fuse could react. You had to limit the current through it some way. Usually, this means you are using a TVS only on signal lines where the current is limited by the existing circuit itself.
answered 9 mins ago
Janka
7,1921718
answered 9 mins ago
Janka
7,1921718
answered 9 mins ago
Janka
7,1921718
answered 9 mins ago
Janka
7,1921718
7,1921718
add a comment |Â
add a comment |Â
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2
Consult UL here, but I seem to recall silicon TVS devices are not permitted for mains protection across the board.
– Matt Young
29 mins ago