Surge Basic

[Elisabetta Buendia]

Whenyou need power distribution in a convenient rackmount configuration, the Middle Atlantic PD-915R is an excellent option! This compact, 1-RU panel provides 9-outlets of 15 amp power, including basic surge and spike protection.

The report, Temporary Basic Income: Protecting Poor and Vulnerable People in Developing Countries estimates that it would cost from $199 billion per month to provide a time-bound, guaranteed basic income to the 2.7 billion people living below or just above the poverty line in 132 developing countries.

The report concludes that the measure is feasible and urgently needed, with the pandemic now spreading at a rate of more than 1.5 million new cases per week, particularly in developing countries, where seven out of ten workers make a living through informal markets and cannot earn money if they are at home.

A Temporary Basic Income would give them the means to buy food and pay for health and education expenses. It is also financially within reach: a six-month Temporary Basic Income, for example, would require just 12 percent of the total financial response to COVID-19 expected in 2020, or the equivalent of one-third of what developing countries owe in external debt payments in 2020.

A Temporary Basic Income is not a silver bullet solution to the economic hardship this pandemic has brought, however. Protecting jobs, expanding support to micro, small and medium enterprises, and using digital solutions to identify and access people who are excluded, are all measures that countries can take.

One way for countries to pay for a Temporary Basic Income would be to repurpose the funds they would use this year to service their debt. Developing and emerging economies will spend $3.1 trillion in debt repayment this year, according to official data. A comprehensive debt standstill for all developing countries, as called for by the UN Secretary-General, would allow countries to temporarily repurpose these funds into emergency measures to combat the effects of the COVID-19 crisis.

COVID-19 has exacerbated existing global and national inequalities and has created new disparities that are hitting the most vulnerable people the hardest. With up to 100 million more people being pushed into extreme poverty in 2020, 1.4 billion children affected by school closures, and record-level unemployment and loss of livelihoods, UNDP predicts that global human development is on course to decline this year for the first time since the concept was introduced.

UNDP is the leading United Nations organization fighting to end the injustice of poverty, inequality, and climate change. Working with our broad network of experts and partners in 170 countries, we help nations to build integrated, lasting solutions for people and planet.

Surge voltages only occur for a fraction of a second. For this reason, they are called transient voltages or transients. They have very short rise times of a few microseconds before they drop off again, relatively slowly, over a period of up to 100 microseconds.

Surge voltages occur as a result of:

Lightning discharges (LEMP)

The technical term for lightning discharge is LEMP. This stands for lightning electromagnetic pulse.

Lightning strikes during storms cause extremely high transient overvoltages. They are much higher than surge voltages that are caused by switching operations or electrostatic discharge. However, they occur a lot less frequently than other causes.

Switching operations (SEMP)

Switching operations are referred to with the abbreviation SEMP. This stands for switching electromagnetic pulse.

In this context, switching operations mean the switching of powerful machines or short circuits in the power supply network. During such operations, significant current changes occur in the affected cables in a split second.

Electrostatic discharges (ESD)

The abbreviation ESD stands for electrostatic discharge.

Here, an electrical charge is transferred when bodies with a different electrostatic potential approach or come into contact with one another. A familiar example of this is when a person becomes charged while walking over a wall-to-wall carpet and then discharges to a metal grounded object, such as a metal rail.

Inductive coupling

This process occurs through the magnetic field of another current-carrying conductor, following the transformer principle. A directly coupled overvoltage causes a surge current with a high rate of increase in the affected conductor.

At the same time, a strong magnetic field is created around this conductor, as is the case in the primary winding of a transformer. The magnetic field induces an overvoltage in other cables in its vicinity, as is the case in the secondary winding of a transformer. The coupled overvoltage is channeled along the cables into the connected device.

Capacitive coupling

This type of coupling primarily occurs via the electric field between two points with a large potential difference. A high potential occurs via the down conductor of a lightning arrester due to a lightning strike. An electrical field is created between the down conductor and other parts with a low potential.

These may be, for example, cables for power supply and signal transmission or devices inside the building. The charge is transferred through the electrical field. This leads to a voltage increase or ultimately an overvoltage in the affected cables and devices.

Common mode voltage

Common-mode voltages [UL] occur in the event of interference caused by surge voltages or high-frequency interference voltages between active conductors and ground. The term asymmetrical is also often used.

Asymmetrical voltages primarily endanger components that are located between active potentials and a grounded ground, as well as the insulation between active potentials and ground. This results in sparkovers on PCBs or between voltage-carrying equipment and grounded housing parts.

Normal mode voltage

Normal-mode voltages [UQ] occur in the event of interference caused by surge voltages or high-frequency interference voltages between the active conductors of a circuit. The terms symmetrical and differential-mode are also used.

Symmetrical surge voltages endanger the voltage and signal input of devices and interfaces. This results in direct overload and destruction of the affected equipment, e.g., in the power supply or signal-processing components.

More often than not, overvoltages which couple into a circuit cause considerable damage to equipment and devices. Devices that are in constant use are at particularly high risk. Here, this damage can result in extremely high costs.

It is not just the replacement or repair of damaged devices that costs money. Even more expensive are long system downtimes or even the loss of software or data.

Every year, the statistics from insurers show high figures for the incidence of loss caused by overvoltages. In the majority of cases, operators of electronic systems are compensated by their insurance for damage to the hardware. However, software damage and system failure frequently remain uninsured, leading to great financial burdens.

According to statistics from German insurers for 2019, the proportion of lightning and surge damage alone makes up a notable proportion. Even though the number of claims has fallen slightly in recent years, around 200 million euros have been paid out annually for household contents and residential building insurance claims. (Source: German Insurance Association, GDV)

Each circuit works with its own specific voltage. Therefore, any voltage increase that exceeds the upper tolerance limit is an overvoltage.

The extent of the damage depends largely on the electric strength of the components used and the energy that can be converted in the affected circuit.

The protective circuit principle describes a concept for complete protection against overvoltages. An imaginary circle should be drawn around the item to be protected. Surge protective devices should be installed at all points where cables intersect this circle. The nominal data of the relevant circuit must be taken into consideration when selecting the protective devices. The area within the protective circuit is therefore protected in such a way that conducted surge voltage couplings are prevented.

The protective circuit concept can be broken down into the following areas:

In order to achieve effective protection, it is important to determine where devices that are in danger are located and what influences represent a danger to the devices. The following figure shows a typical single-family home used as an example to illustrate the location of the individual protection zones.

The inductive resistance can only be reduced by shortening the cable length or connecting discharge paths in parallel. To minimize the total impedance of the discharge path and therefore the residual voltage, mesh-shaped equipotential bonding that is as tightly meshed as possible is the best technical solution.

Complete protection can only be achieved through complete isolation or through complete equipotential bonding. However, since complete isolation is impossible for many practical applications, only complete equipotential bonding remains.

To achieve this, all electrically conductive parts must be connected to the equipotential bonding system. Protective devices are used to connect live cables to the central equipotential bonding. In the event of an overvoltage, they are conductive and short circuit the overvoltage. Damage from overvoltages can therefore be prevented effectively.

Various equipotential bonding systems can be created:

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