Surge Diverters 3.3kV 11kV | Metrosil VSD Surge Diverter
VSD Surge Diverters
Metrosil VSD are surge diverters used to limit the amount of voltage reaching an application, that protect MV HV (Medium & High Voltage) transformers and switchgear from electrical surges – the MV HV surge diverters are designed to provide effective protection against voltage surges that may result from the operation of power distribution switchgear.
The VSD surge diverters are typically used to protect power and electrical networks operating at 3.3kV, 6.6kV and 11kV.
They are suitable for systems having working voltages from 3.3kV to 11kV rms. Each MV surge 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.
Metrosil VSD Surge Diverter is suitable for use on applications where medium voltage switching is infrequent but stored energy levels are high.
Metrosil VSD’s are particularly suited to the protection of all types of MV-HV transformers, generators, motors (especially if there is a likelihood of switching in the stalled or accelerating condition), and any device/load where impulse voltage withstand level is low or not known. For all VSD types the surge current rating is limited to 30A and no de-rating is required dependent upon the number of surge events.
Metrosil VSD’s are available with standard end caps or with various alternatives to match customer requirements.
Surge Diverters 3.3kV 11kV
- Suitable for use in systems with working voltages from 3.3kV to 11kV rms
- Provides optimum protection under severe switching surge conditions
- Protects all types of MV HV transformers, generators and motors
Maintenance is not necessary – it is recommended that MV surge 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 medium voltage surge diverters are voltage limiting devices, they must be disconnected from the system before applying any insulation proof testing voltage, otherwise the surge diverters will be damaged.
Metrosil Surge Diverters
Dimensions, Performance and Selection
The maximum energy rating figures are shown in the below table and assume a cooling period of approximately 3 hours between sequential surge events.
|Maximum Impulse 1.2/50μsec Sparkover Voltage||Residual
|mm||mm||mm||mm||kV rms||kV rms||kV||kV||A||kJ|
Surge Diverter RESPONSE TIME
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 spark over tests. Spark gaps 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 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 in Figure 2 above shows the results of the impulse voltage tests on a VSD/S6 diverter. 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.