SURGE DIVERTERS TYPE VSD
SURGE DIVERTERS TYPE VSD Introduction
Response time
Surge diverters type VSD have been designed to provide effective protection of motor and transformer insulation against voltage surges which may sometimes result from the operation of switchgear.
Modern switchgear in conjunction with modern equipment and cables can produce transient switching overvoltages with a faster rate of rise than the standard 1.2/50µsec impulse wave used for impulse sparkover tests.
They are suitable for systems having working voltages from 3.3kV to 11kV rms. Each diverter consists of a spark-gap assembly in series with a number of Metrosil non-linear resistors housed in a ceramic body. The Metrosil resistors and spark-gaps have been specially developed to provide optimum protection under severe switching surge conditions and are individually tested for selective assembly.
Sparkgaps used for limiting these overvoltages are subject to statistical scatter and an increasing mean value of sparkover as the rate of rise of voltage increases.
The curve shows that in the case of the VSD/S6, the overvoltage is clipped at a maximum of 130% of the 100%, 1.2/50µsec sparkover voltage. These results indicate a very satisfactory response of the VSD diverter to transient voltages with rates of rise greater than that for the associated 1.2/50µsec 100% sparkover test wave.
The gaps used in the VSD diverters have been designed to minimise both the statistical scatter and the increase in mean sparkover value at the higher rates of rise. The graph shows the results of the impulse voltage tests on a VSD diverter.
Sparkover voltage percentage of l E C 1.2/50 wave 100% sparkover level.
140 120 100
Applications
80
VSD surge diverters are intended for use on power distribution switching applications where switching is infrequent but stored energy levels are high. VSDs are particularly suited to the protection of all types of transformers, generators, motors (especially if there is a likelihood of switching in the stalled or accelerating condition) and any device or load where impulse voltage withstand level is low or not known.
60 40
VSD/S6
20 0
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Time to sparkover from virtual origin, µsec.
Types VSDs are available with standard end caps (as shown in the diagram) or with various alternatives to match customers’ requirements.
Performance Type
VSD/S3
VSD/S6
VSD/S11
System working voltage AC rms
3.3kV
6.6kV
11kV
Minimum AC rms sparkover voltage
5.5kV
11kV
18kV
Maximum impulse 1.2/50µsec sparkover voltage
11kV
22kV
36kV
Residual voltage at 30A
8kV
16kV
26.5kV
Maintenance No maintenance is necessary or possible. It is recommended that diverters be replaced when the main operational components of the switchgear are changed or if there has been some severely abnormal switching condition or switchgear failure. As these diverters are voltage-limiting devices, they must be disconnected from the system before applying any insulation proof testing voltage, otherwise the diverters will be damaged.
SILICON CARBIDE SURGE PROTECTION
www.metrosil.com
August 2010
SURGE DIVERTERS TYPE VSD Dimensions (mm) VSD/S3
VSD/S6
VSD/S11
A
130
200
200
B
40
40
40
C
195
265
265
D
32
32
32
E
172
242
242
F
43
43
43
G
85
155
155
A
G
12mm x 9mm mounting holes B
D F
E C
SILICON CARBIDE SURGE PROTECTION Any recommendation or suggestion relating to the use, storage, handling or properties of the products supplied by M&I Materials Ltd either in sales and technical literature or in response to a specific enquiry or otherwise is given in good faith, but it is for the customer to satisfy itself of the suitability of the product for its own particular purposes. ® Registered Trade Mark
www.metrosil.com
August 2010
Response time
Surge diverters type VSD have been designed to provide effective protection of motor and transformer insulation against voltage surges which may sometimes result from the operation of switchgear.
Modern switchgear in conjunction with modern equipment and cables can produce transient switching overvoltages with a faster rate of rise than the standard 1.2/50µsec impulse wave used for impulse sparkover tests.
They are suitable for systems having working voltages from 3.3kV to 11kV rms. Each diverter consists of a spark-gap assembly in series with a number of Metrosil non-linear resistors housed in a ceramic body. The Metrosil resistors and spark-gaps have been specially developed to provide optimum protection under severe switching surge conditions and are individually tested for selective assembly.
Sparkgaps used for limiting these overvoltages are subject to statistical scatter and an increasing mean value of sparkover as the rate of rise of voltage increases.
The curve shows that in the case of the VSD/S6, the overvoltage is clipped at a maximum of 130% of the 100%, 1.2/50µsec sparkover voltage. These results indicate a very satisfactory response of the VSD diverter to transient voltages with rates of rise greater than that for the associated 1.2/50µsec 100% sparkover test wave.
The gaps used in the VSD diverters have been designed to minimise both the statistical scatter and the increase in mean sparkover value at the higher rates of rise. The graph shows the results of the impulse voltage tests on a VSD diverter.
Sparkover voltage percentage of l E C 1.2/50 wave 100% sparkover level.
140 120 100
Applications
80
VSD surge diverters are intended for use on power distribution switching applications where switching is infrequent but stored energy levels are high. VSDs are particularly suited to the protection of all types of transformers, generators, motors (especially if there is a likelihood of switching in the stalled or accelerating condition) and any device or load where impulse voltage withstand level is low or not known.
60 40
VSD/S6
20 0
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Time to sparkover from virtual origin, µsec.
Types VSDs are available with standard end caps (as shown in the diagram) or with various alternatives to match customers’ requirements.
Performance Type
VSD/S3
VSD/S6
VSD/S11
System working voltage AC rms
3.3kV
6.6kV
11kV
Minimum AC rms sparkover voltage
5.5kV
11kV
18kV
Maximum impulse 1.2/50µsec sparkover voltage
11kV
22kV
36kV
Residual voltage at 30A
8kV
16kV
26.5kV
Maintenance No maintenance is necessary or possible. It is recommended that diverters be replaced when the main operational components of the switchgear are changed or if there has been some severely abnormal switching condition or switchgear failure. As these diverters are voltage-limiting devices, they must be disconnected from the system before applying any insulation proof testing voltage, otherwise the diverters will be damaged.
SILICON CARBIDE SURGE PROTECTION
www.metrosil.com
August 2010
SURGE DIVERTERS TYPE VSD Dimensions (mm) VSD/S3
VSD/S6
VSD/S11
A
130
200
200
B
40
40
40
C
195
265
265
D
32
32
32
E
172
242
242
F
43
43
43
G
85
155
155
A
G
12mm x 9mm mounting holes B
D F
E C
SILICON CARBIDE SURGE PROTECTION Any recommendation or suggestion relating to the use, storage, handling or properties of the products supplied by M&I Materials Ltd either in sales and technical literature or in response to a specific enquiry or otherwise is given in good faith, but it is for the customer to satisfy itself of the suitability of the product for its own particular purposes. ® Registered Trade Mark
www.metrosil.com
August 2010
