Surge Diverters 1.2kV 15.5kV | Metrosil SVL Surge Diverter

SVL Surge Diverters

Metrosil SVL 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 specifically developed for switching applications where the surge to be suppressed may have a fast rise time but low energy content.

The SVL surge diverters are typically used to protect power and electrical networks operating at 3.3kV, 6.6kV, 11kV and 15kV medium voltages. These metal oxide varistors have highly non-linear volt-amp characteristics and therefore provide excellent protection against overvoltages. The response time of the metal oxide elements to transient overvoltages is of the order of 50 nanoseconds. Surge diverters are recommended for use with any device where the withstand impulse voltage is low and high-energy absorption is not required.

Surge Diverters Applications

• the protection of MV HV transformers where the frequency of switching is high, particularly if the transformers are lightly loaded
• the protection of MV HV motors, especially if there is a likelihood of switching in the stalled or accelerating condition

SVL surge diverters are available in two formats. The standard format has a M6 ISO coarse threaded stud at each end, whereas the flying lead version has one M6 stud connection and an insulated 400mm long flexible lead to aid installation.

The MV surge diverters are rated for ambient temperatures up to 70°C.

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Surge Diverters 1.2kV 15.5kV

Benefits

• Rated surge diverter voltages from 1.2kV to 15.5kV
• Constructed from metal oxide varistors, offering excellent protection levels
• Suitable for loads which are switched with vacuum contactors

Maintenance

No maintenance is necessary as these MV surge diverters are designed for a lifetime equivalent to that of the switch with which it operates. As with Metrosil VSD surge diverters, SVL diverters must be disconnected from the power system before applying any insulation proof testing voltage, otherwise the MV surge diverters will be damaged.

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SELECTION BY VOLTAGE

Each surge diverter consists of a number of metal oxide varistors, connected in series and encapsulated in a PVC container using a polyurethane resin. Dimensions of the diverters can be seen in Figure 1.

The MV surge diverters are available with maximum voltage ratings from 1.2kV to 15.5kV rms and can be connected either between the supply lines or between each supply line and earth. Selection must be based on the maximum voltage that may be impressed on the diverter during both normal and abnormal system conditions.

This voltage will depend on the system earthing arrangement and must not exceed the maximum diverter rated voltage as shown in the below table..

Type	Body Length A	Maximum Diverter Rated Voltage	Maximum Surge Protection Level at 10A Discharge	Maximum System Voltage L-L		Current Rating 8/20 μs Waveform**	Energy Rating 8/20 μs Waveform**
				Diverter connected L-N system effectively earthed as defined below*	Diverter connected L-Nsystem non-effectively earthed (or L-L)
	mm	kV rms	kV pk	kV rms	kV rms	A	J
SVL1	50	1.2	4	1.5	1.2	150	11
SVL2	60	2.4	7	3	2.4	150	21
SVL3	75	3	8.5	3.75	3	150	27
SVL4	110	4	11.5	5	4	150	38
SVL6	110	6	16.5	7.5	6	150	54
SVL8	160	8	22.5	10	8	150	75
SVL9	160	9.5	27	12	9.5	150	86
SVL10	200	10.5	30	13.5	10.5	150	97
SVL12	200	12	33	15	12	150	108
SVL15	240	15.5	43.5	19	15.5	150	140

* The coefficient of earthing of a three phase system is defined as follows: “The ratio of the highest rms voltage to earth of the sound phase or phases at the point of application of a diverter during a line-to earth fault (irrespective of the fault location), to the highest line-to-line rms voltage, expressed as a percentage of the latter voltage. If this ratio is less than 80%, then the system is regarded as effectively earthed. If the ratio is greater than 80%, then the system is regarded as non-effectively
earthed.”
** Based on 10,000 surge events.

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CURRENT AND ENERGY RATINGS

Metal oxide varistors (MOVs) have to be de-rated from their published figures according to the number and size of the current surges expected during the required lifetime of the device. SVL surge diverters contain MOVs, but they have been chosen so that, for the application for which they have been designed, de-rating is not normally a consideration. For SVL diverter applications
outside the current and energy rating parameters indicated in the above table, please contact T&D.

 See also: Sheath Voltage Limiters MV HV | Surge Arresters MV HV | Fuses MV HV | Bushings MV HV | Joints & Terminations MV HV

Data Sheets

• Surge Diverters 1.2kV 15.5kV Metrosil SVL Surge Diverter
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