DMOP-5 & DMOP-10

Distribution Class, Gapless, Metal-Oxide
DMOP Type Surge Arresters


DMOP - 5
DMOP - 10

Nominal Discharge Current : 5 kA (8/20 µs)
Distribution Class, Heavy Duty : DMOP-10
Nominal Discharge Current : 10 kA (8/20 µs)
Governing Specification : IEC 99-4
Installation Site : Outdoor, 0-1200 m. Altitude
Rated Frequency : 48-62 Hz.

Nominal Discharge Current : 10 kA (8/20 µs)
Distribution Class, Heavy Duty : DMOP-10
Nominal Discharge Current : 10 kA (8/20 µs)
Governing Specification : IEC 99-4
Installation Site : Outdoor, 0-1200 m. Altitude
Rated Frequency : 48-62 Hz.

Metal Oxide Arresters

For arresters of type DMOP-5 and DMOP-10, DİSAŞ works with one of the world's leading suppliers of metal-oxide blocks. The arresters are manufactured under a technical co-operation afreement, whereby blocks are imported and the complete arresrters are then assembled and tested in DİSAŞ's own plant.

The quality of the varistors are guaranteed by design test reports from independent international laboratories, together with the qulity assurance system of the supplier. Meanwhile the varistors are also being testedat DİSAŞ's own laboratories upon arrival.

The use of highly non-linear metal oxide varistors permits the elimination of the internal series gap structure. The metal-oxide blocks combine protective characteristics with steady state performance to maximize protection over many years of service.

The varistors are put together by means of an epoxy-based wrapping system to from one single and rigid column of metal-oxide blocks. This special design not only ensures a higher reliability against high current surges, but it also enables the arrester to establish an increased steady-state performance.

Performance & Application

The gapless design means improved response to surges with fast rates of rise (i.e. Steep current surges). The stabilitiy of the protective characteristics of “DMOP” results in more consistent protection. This becomes increasingly important as equipment insulting capabilities degrade with time.

Metal-Oxide arresters “Maximum Continuous Operating Voltage” (MCOV) designates the maximum power frequency voltage that may be applied continuously through the arrester in service. Selection of the appropriate DMOP-rated voltage is made on the basis that the maximum line-to-ground voltage on the system does not exceed the MCOV of the arrester.


Rigit quality control standards ensure that all material conforms to exacting engineering specifications. Each complete arrester is subjected to seal leakage test to ensure the integrity of the sealing system and electrical tests to measure leakage current (resistive and capacitive components), reference voltage and partial discharge level of arrester.

All above mentioned tests are performed on each complete arrester according to IEC 99-4.


Pressure Relief

In recent years, DİSAŞ developed its own design for the pressure relief system of DMOP-type arresters. This unique design enables the arrester to strike out the internal arc ( in the case of a high surge due to a fault) within 1 millisecond, even for an arrester with the longest unit o the porcelain housing. Type test are performed at the highest current level of pressure relief class (i.e. At 16kA rms for DMOP-5 kA, at 20 kA mrs for DMOP-10 kA arresters). The performances are documented by design test reports from CESI laboratories in Italy.

Ground Lead Disconnector (GLD)

If required, DMOP-5 and DMOP-10 arresters can be supplied with a GLD device. GLD helps prevent line lockout by disconnecting a failed arrester from the system and serves as an indicating device that the failed arrester needs replacement.

The GLD that DİSAŞ supplies with its “DMOP” model arresrters is the only disconnector on the world which has a design test report from an independent international laboratory (CESI) for its operation.

GLD has to be earthed through the earth connection cable that is normally supplied with DMOP arresters.

Quality Assurance

Already established rules of extensive quality control in our production lines easily met the requirements of ISO-9002 certified by Turkish Standards Institution (TSE) since 1996.

Metal-Oxide varistors are purchased from one of the world's largest varistors manufacturers and they are tested as disaş laboratories upon arrival.

The varistors receice 100% routine tests before assembly into an arrester. According to the results of these tests, each varistor is selected for final assembly based on residual voltage, to assure the residual voltage of the complete arrester will not exceed standard values.

Final assembly, all routine tests required by IEC 99-4 are performed on each arrester. Only the accepted complete arresters continue on for final packaging and shipping.

Arrester Mounting

Standard Suppy: The standard supply of DMOP arrester's nuts & bolds are made of hot-dip galvanized steel.

DMOP arresters with rated voltage 30 kV or above are equipped with broad fixing beackets, whereas those with rated voltage below 30 kV are equipped with narrow fixing brackets.

A flexable earth connection cable, located between the arrester's lower cap and fixing bracket will provide the user an easy connection of the arrester to the ground.

Optional Devices: If required, DMOP-type arresters can be supplied with a Ground Lead Disconnector (GDL) device. GLD can easily be assembled at the ground terminal of the arrester.

If a base-mounting system is required for DMOP type arresters, they would be suppiled with a “Special Base”. For “base mounting” DMOP arresters GLD and fixing brackets are not used.

If NEMA-mounting bracket is required, DMOP typr arresters can be supplied with brackets. These are also made o hot-dip galvanized steel.

- Long Duration Current Impulse : 250 A-peak 2000 µsec.
- TOV Capability : Duration; 1 sec : TOV = 1.55 x Umcov
- Duration; 10 sec : TOV = 1.5 x Umcov
- High Current Impulse Withstand : 100 kA-peak (4/10 µs.)
- Pressure Relief Capability : 20 kA rms, sym

Ur : Rated Voltage
Umcov : Max. Continuos Operating Voltage of the Arrester
Usteep : Steep Current Impulse Max. Residual Voltage
Usw : Switching Current Impulse Max. Residual Voltage
Ures : Lightning Impulse Current Residual Voltage (8/20 µs-wave)
TOV : Temporary Overvoltage Capability


©2011 Disaş AŞ