Ps 135:7 "The Lord Jesus causes the vapours to ascend from the ends of the earth, He makes lightning for the rain, He brings the wind out of His treasuries"

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Drop Out surge arrestors

Function of the Drop out surge arrestor

Drop out surge arrestors are over-voltage protection devices. Download LLT Arrestor spec.pdf (File Size:80kb)

Drop out surge arrestors are MOV based devices that are designed to protect against the damaging effects of spikes and transients caused by lightning, utility switching, isolation arching, electrical motor cycling, or any other sudden change in the electrical power flow on incoming AC power lines. Lightning damage, is responsible for a large percentage of over-voltage occurrences, these are either direct strikes to a line or induced voltages onto the line. (strikes within 40m of a line).

Drop out surge arrestors prevent flashover between phases, prevent damage to poles and protect transformers from lightning damage and surges. Live Line Arrestors can be intelligently placed on lines in problem areas where equipment is consistently damaged.

The placing of Drop out surge arrestors has proven to be more cost effective than improving the insulation of poor performing lines. A spent Drop out surge arrestor can be exchanged for a new unit within minutes with the aid of a link stick and with the system energized. This eliminates unnecessary outages and lost revenue for the electrical utility.


  • Designed to prevent over-voltage caused by lightning transients or surges.
  • On breakdown of the MOV blocks, the system frequency disconnects the faulty surge arrestor via the GLD (Ground lead disconnector). This unit, is placed at the bottom of the surge arrestor and is back in appearance.
  • The drop out surge arrestor, falls into the open position and can be replaced live line.
  1. Changed Live Line (easy drop out function).
  2. Changed from Ground.
  3. Easily identified when blown.
  4. Safer
  5. Easier maintenance.
  6. Easy & Effective replacement.
  7. Elimination of outage times.
  8. Cost Effective method of protecting an area.
  9. Arrestor can effectively be opened when there are Problematic Arrestors or GLD’s.
  10. Easy isolation during fault finding.
  11. Operational Staff relieved of Dangerous situations.
  12. Operational Staff response to Arrestor maintenance improved.
  13. On the Spot replacement.
  14. Building up Staff of attitudes by providing easier maintenance of Arrestor unit.
  15. Fear Factor of Operational staff removed when working on high voltage equipment.
  16. Line Inspections a pleasure.
  17. Spent Arrestor easily noticed for replacement from previous Lightning Incident.
  18. Risk of equipment exposure eliminated.
  19. Faulty units immediately replaced, no postponing of the maintenance effort.
  20. Used at Distribution line ends and T-offs (voltage doubling points)
Drop out surge arrestor Installation Guidelines

    7 Guidelines for successful installation

  1. Install Drop out surge arrestors at strategic poles on poor performing lines. (poorly insulated lines).
  2. Drop out Arrestors installed as firewalls to assist surge arrestors placed at the transformer. eg. These surge arrestors are often placed one pole away from a critical transformer installation, assisting the surge arrestors at the Transformer Combi Unit .
  3. Install Drop out Arrestors at poles that are consistently struck by lightning causing split poles and damage to lines. Field services engineers have knowledge (data) of such points on their feeders.
  4. Install Drop out Arrestors at the end of the overhead line, where voltage doubling occurs and where underground cable needs to be protected against voltage refraction. Prevent underground cables from being damaged.
  5. Place Drop out Arrestors at points on the overhead lines that are supposedly protected by high masts but where equipment is still lost.
  6. Place a set of Drop out Arrestors to prevent poor performing lines from causing ARC’s and tripping on the overhead lines.
  7. Install a set of Drop out Arrestors rather than conventional arrestors, there effective replacement will prevent the need for an outage, and improve the customer’s quality of supply.
Drop out Arrestors Accessories

Replacing a Drop out arrestor

Changing a Drop out Arrestor is a task that takes 10-15min, with no customer outage. It can be done by one operator, but may be easier, if two people are available. See the following 3 easy steps.

1. Insert the surge arrestor.

The surge arrestor has a circular ear piece that fits any standard link stick.
2. Lift the unit.

  • Always wear PPE. (Helmets)
  • The units weigh the following:
    • 3kv-11kv = 5kg
    • 22kv = 7kg
    • 33kv = 10 kg
3. Insert the drop out arrestor.

  • Lifting the unit into the air , is no problem.
  • The system voltage is still live line, and the old unit is replaced with a new one within minutes
Available at LLT sales :

Contact sales at :
Int: (002718) 468 5080
Tel: (018) 468 5080
Fax: (086) 667 2900
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