RISSP stands for Record of Inter System Safety Precautions . [1] It is a written record of inter-system safety precautions to be compiled in accordance with the provisions of Operating Code no. 8 (OC8). [2] Where a High Voltage electrical boundary occurs, for instance between a power station and electrical utility, the safety controllers each side of the boundary must co-ordinate their activities. For the electrical transmission system in England, Wales and Scotland, the Ofgem-defined industry standard document OC8 of the Grid code defines how safety precautions can be managed with the Record of Inter System Safety Precautions (RISSP) independently from the safety rules of the connected parties. The purpose of the RISSP is to guarantee that safety precautions provided by a third-party can be quoted in a safety document so that work can take place.
The RISSP form must have a uniquely identifying number, provided by the party requesting safety precautions. To achieve this, all parties connected to the national grid must have a RISSP prefix code. These are, in general, abbreviations of the company name at the time it applied for its code. All RISSPs have the suffix 'R'. The requester states the location and equipment that requires the RISSP. The implementer then states the location and nature of the precautions provided for adequate safety of that equipment.
Some interfaces may include more than two parties, for instance on substation busbars (BB). This may require one request via a party on the BB to go via the BB controller to the other parties. It is then for the BB controller to get all required safety from other parties to cascade on to the initial requesting controller. This is sometimes referred to as a cascading RISSP. Where a third-party making a request for safety precautions controls some of the other infeeds to an interface on which safety has been requested (such as a distribution network operator who has more than one circuit on a BB, but is requesting safety for just one of those circuits) it is up to the requester themselves to control the linked safety precautions to ensure that safety from the interface. This is often referred to as linkage. It is possible to have both linkage and cascading in a single job, requiring use of RISSP forms with multiple users.
In addition it is possible for to request safety in multiple directions, which results in controllers having both requesting and implementing RISSPs in force simultaneously. These RISSPs may be cascading and/or linkage. It is not possible to have RISSPs going in multiple directions if HV testing is taking place across a boundary. In these circumstances only a single safety document can be in force at any one time and any RISSPs in place can only be to ensure the safety precautions for this document.
RISSPs do not have to be from one company to another, only one control boundary to another. Thus two distribution network operators owned by the same parent company but with different geographical areas of responsibility use RISSPs with each other. Also, the boundary between a High Voltage controller and a Low Voltage controller can be controlled by the RISSP process. This most commonly occurs with the fuses/links between an auxiliary transformer and a substation's 415 volt AC supplies.
RISSPs can only be agreed to and signed by a suitably authorised person. Any company that is connected to the grid must have somebody authorised available or on call at all times.
In electrical engineering, ground or earth may be a reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the Earth.
The electric power industry covers the generation, transmission, distribution and sale of electric power to the general public and industry. The commercial distribution of electric power started in 1882 when electricity was produced for electric lighting. In the 1880s and 1890s, growing economic and safety concerns lead to the regulation of the industry. What was once an expensive novelty limited to the most densely populated areas, reliable and economical electric power has become an essential aspect for normal operation of all elements of developed economies.
A power outage is the loss of the electrical power network supply to an end user.
A substation is a part of an electrical generation, transmission, and distribution system. Substations transform voltage from high to low, or the reverse, or perform any of several other important functions. Between the generating station and consumer, electric power may flow through several substations at different voltage levels. A substation may include transformers to change voltage levels between high transmission voltages and lower distribution voltages, or at the interconnection of two different transmission voltages. They are a common component of the infrastructure. There are 55,000 substations in the United States.
Serial Peripheral Interface (SPI) is a de facto standard for synchronous serial communication, used primarily in embedded systems for short-distance wired communication between integrated circuits.
A remote terminal unit (RTU) is a microprocessor-controlled electronic device that interfaces objects in the physical world to a distributed control system or SCADA system by transmitting telemetry data to a master system, and by using messages from the master supervisory system to control connected objects. Other terms that may be used for RTU are remote telemetry unit and remote telecontrol unit.
An electricity meter, electric meter, electrical meter, energy meter, or kilowatt-hour meter is a device that measures the amount of electric energy consumed by a residence, a business, or an electrically powered device.
A variable-frequency drive is a type of AC motor drive that controls speed and torque by varying the frequency of the input electricity. Depending on its topology, it controls the associated voltage or current variation.
Power-system automation is the act of automatically controlling the power system via instrumentation and control devices. Substation automation refers to using data from Intelligent electronic devices (IED), control and automation capabilities within the substation, and control commands from remote users to control power-system devices.
A microgrid is a local electrical grid with defined electrical boundaries, acting as a single and controllable entity. It is able to operate in grid-connected and in island mode. A 'stand-alone microgrid' or 'isolated microgrid' only operates off-the-grid and cannot be connected to a wider electric power system.
In-system programming (ISP), or also called in-circuit serial programming (ICSP), is the ability of some programmable logic devices, microcontrollers, chipsets and other embedded devices to be programmed while installed in a complete system, rather than requiring the chip to be programmed prior to installing it into the system. It also allows firmware updates to be delivered to the on-chip memory of microcontrollers and related processors without requiring specialist programming circuitry on the circuit board, and simplifies design work.
Phase-fired control (PFC), also called phase cutting or phase-angle control, is a method for power limiting, applied to AC voltages. It works by modulating a thyristor, SCR, triac, thyratron, or other such gated diode-like devices into and out of conduction at a predetermined phase angle of the applied waveform.
A phasor measurement unit (PMU) is a device used to estimate the magnitude and phase angle of an electrical phasor quantity in the electricity grid using a common time source for synchronization. Time synchronization is usually provided by GPS or IEEE 1588 Precision Time Protocol, which allows synchronized real-time measurements of multiple remote points on the grid. PMUs are capable of capturing samples from a waveform in quick succession and reconstructing the phasor quantity, made up of an angle measurement and a magnitude measurement. The resulting measurement is known as a synchrophasor. These time synchronized measurements are important because if the grid’s supply and demand are not perfectly matched, frequency imbalances can cause stress on the grid, which is a potential cause for power outages.
In electrical engineering, earth potential rise (EPR), also called ground potential rise (GPR), occurs when a large current flows to earth through an earth grid impedance. The potential relative to a distant point on the Earth is highest at the point where current enters the ground, and declines with distance from the source. Ground potential rise is a concern in the design of electrical substations because the high potential may be a hazard to people or equipment.
In an alternating current (AC) electric power system, synchronization is the process of matching the frequency, phase and voltage of a generator or other source to an electrical grid in order to transfer power. If two unconnected segments of a grid are to be connected to each other, they cannot safely exchange AC power until they are synchronized.
A grid-tie inverter converts direct current (DC) into an alternating current (AC) suitable for injecting into an electrical power grid, at the same voltage and frequency of that power grid. Grid-tie inverters are used between local electrical power generators: solar panel, wind turbine, hydro-electric, and the grid.
An electrical grid is an interconnected network for electricity delivery from producers to consumers. Electrical grids consist of power stations, electrical substations to step voltage up or down, electric power transmission to carry power long distances, and lastly electric power distribution to individual customers, where voltage is stepped down again to the required service voltage(s). Electrical grids vary in size and can cover whole countries or continents. From small to large there are microgrids, wide area synchronous grids, and super grids.
A grid code is a technical specification which defines the parameters a facility connected to a public electric grid has to meet to ensure safe, secure and economic proper functioning of the electric system. The facility can be an electricity generating plant, a consumer, or another network. The grid code is specified by an authority responsible for the system integrity and network operation. Its elaboration usually implicates network operators, representatives of users and, to an extent varying between countries, the regulating body.
A distribution management system (DMS) is a collection of applications designed to monitor and control the electric power distribution networks efficiently and reliably. It acts as a decision support system to assist the control room and field operating personnel with the monitoring and control of the electric distribution system. Improving the reliability and quality of service in terms of reducing power outages, minimizing outage time, maintaining acceptable frequency and voltage levels are the key deliverables of a DMS. Given the complexity of distribution grids, such systems may involve communication and coordination across multiple components. For example, the control of active loads may require a complex chain of communication through different components as described in US patent 11747849B2
This glossary of electrical and electronics engineering is a list of definitions of terms and concepts related specifically to electrical engineering and electronics engineering. For terms related to engineering in general, see Glossary of engineering.
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