About Power

Understanding transient and surge
Transient and surge are temporary rise in voltage and current on an electrical circuit. Their voltage ranges are greater than 2000 volt and current ranges are greater than 100 ampere. Typical rise time is in the 1 to 10 microsecond range. The transient or surge is the most common power problems and its compacts are caused significant damages such as electrical or electronic equipments failure, frequent downtime, lost data, lost time and business downtime, etc.

The causes of transient and surge
There are several causes of transient or surge.

  • Natural phenomena like rainstorm, storm, lightning and earthquake, etc.
  • The utility power supplies failure
  • High-powered electrical motors switch on and off
  • High-powered equipments
  • Electrical noise
    Etc.

The Surge Protector meaning
Surge Protection Devices (SPD), Surge Suppression Equipment (SSE) and Transient Voltage Surge Suppressor (TVSS) are different terms that are used to describe the same device, Surge Protector.
The Surge Protector is a device that absorbs and diverts the excess voltage and current from transient or surge. These excess energy can cause damages in electrical and electronic equipments, process control instruments-equipments.

Two main functions of the surge protector are

  1. Provides low impedance path or place for a rise in voltage and current to equalize as ground
  2. Absorbs and diverts the excess voltage and current to the providing place to protect the effects of transient or surge

The Surge Protector types
The Surge Protector are classified into two types as

  1. Filter is a device that serves as barrier to high frequency current that is often noise, while allowing the low frequency power current to pass through unaffected.
  2. Transients Diverter is a device that presents a very low impedance path to ground whenever the voltage across the device exceeds certain value, but reduces the voltage that could be present to the sensitive equipments.
    The Surge Protector general functions
    The Surge Protector is designed to divert as much of transient energy away from the loads as possible by providing a lower impedance path and then address the excess energy to the provide place, ground.

The Surge Protector components
The type of Surge Protector that use in any application is different, and also consisted components are difference. But the same purpose of Surge Protector is to efficiently protect from the temporary rise in voltage and current, to be high reliability and to fast respond to excess energy. The most common Surge Protector components are used to provide the low impedance pathway. These components include Metal Oxide Varistor (MOV), Gas Discharge Tube (GDT) and Silicon Avalanche Diode (SAD), etc. or combination of these components.

 

Each of these Surge Protector components has features as the followings

  • MOV (Metal Oxide Varistor) is very fast responding to transient or surge (20 nsec), but it has difficulties with large currents (100 A) that shorten the life cycle of the MOV. Under normal conditions, the MOV presents itself as a high impedance device but when the voltage is out of range, the resistance of the MOV drops rapidly to provide a low impedance path of flow. Moreover, it is high handling voltage and current capability.
  • Gas Discharge Tube (GDT) ) can handle very large voltage (20 kV) and current (2500 A) surges, but relatively is slow responding to transient and surge.
  • Silicon Avalanche Diode (SAD) is fast (5 nsec) and can handle large currents (1000 A), but are susceptible to dv/dt and peak voltage failure modes.
  • Other combinational devices are use resistors, capacitors and/or SCRs in conjunction with these Surge Protector components

The Surge Protector advantages
The Surge Protector can help to protect from the damages in the connected electrical and electronic equipments, particularly computers. All of below examples are

  • Natural phenomena like lightning
  • The utility power supply failure
  • Inductive and sensitive equipments
  • Electrical noise

The Surge Protector installation
The Surge Protector is typically applied at several points throughout a facility. This device is classified into three categories.
  • Category A type equipment is applied at the individual circuit level for individual protection of a specific piece of equipment such as computers, weighting bridges, measuring equipments, process control equipments and DC power supplies, etc.
  • Category B type equipment is applied at the distribution panels or switchboards. The protection at this location is very effective in suppressing the much more frequent internally generated transients, ever-changing transient conditions, especially, sensitive equipments and equipments, which are fed from the substations.
  • Category C type equipment is applied at the service entrance to be the defense against externally caused power disruptions. This installation will help guard against lightning strike entering a facility via the power line.

The Surge Protector applications
The Surge Protector is suitable to use in every applications that consume the electricity (the utility power supplies or the locally generated), telephone lines (such as modem, fax, data, etc.), computer data lines and communication lines, etc. These applications need the effective and reliable surge protectors.

  • Computers and peripherals such as printer, monitor, speaker and modem, etc.
  • PABX and communication equipments, etc.
  • Medical equipments, surgical equipments and scientific equipments, etc.
  • Weighting bridges and measuring equipments, etc.
  • Electrical equipments
  • Security systems

 
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