A sequence of events recorder (SER) is an intelligent standalone microprocessor based system, which monitors external inputs and records the time and sequence of the changes. Sequence of events recorders usually have an external time source such as a

GPS The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite sy ...

radio clock A radio clock or radio-controlled clock (RCC), and often (incorrectly) referred to as an atomic clock is a type of quartz clock or watch that is automatically synchronized to a time code transmitted by a radio transmitter connected to a time s ...

. When wired inputs change state, the time and state of each change is recorded. SERs enable rapid

root cause analysis In science and engineering, root cause analysis (RCA) is a method of problem solving used for identifying the root causes of faults or problems. It is widely used in IT operations, manufacturing, telecommunications, industrial process control, ...

after multiple events have occurred due to the secure recording of the

sequence of events Time is the continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence events, to ...

in the order of occurrence. SERs are therefore utilized as a diagnostic tool to minimize plant downtime. SERs are often interfaced with a

SCADA Supervisory control and data acquisition (SCADA) is a control system architecture comprising computers, networked data communications and graphical user interfaces for high-level supervision of machines and processes. It also covers sensors and ...

system,

distributed control system A distributed control system (DCS) is a computerised control system for a process or plant usually with many control loops, in which autonomous controllers are distributed throughout the system, but there is no central operator supervisory contro ...

(DCS),or

programmable logic controller A programmable logic controller (PLC) or programmable controller is an industrial computer that has been ruggedized and adapted for the control of manufacturing processes, such as assembly lines, machines, robotic devices, or any activity tha ...

(PLC). SER reports are used by electrical engineers to analyze large and small electrical system blackouts. After the

Northeast blackout of 2003 The Northeast blackout of 2003 was a widespread power outage throughout parts of the Northeastern and Midwestern United States, and most parts of the Canadian province of Ontario on Thursday, August 14, 2003, beginning just after 4:10 p.m. ...

, the

North American Electric Reliability Corporation The North American Electric Reliability Corporation (NERC) is a nonprofit corporation based in Atlanta, Georgia, and formed on March 28, 2006, as the successor to the North American Electric Reliability Council (also known as NERC). The original N ...

(NERC) specified that electrical system data should be time-tagged to the nearest

millisecond A millisecond (from '' milli-'' and second; symbol: ms) is a unit of time in the International System of Units (SI) equal to one thousandth (0.001 or 10−3 or 1/1000) of a second and to 1000 microseconds. A unit of 10 milliseconds may be calle ...

. In 1984 The Tetragenics Company, a subsidiary of the Montana Power Company, introduced the first

remote terminal unit 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 (supervisory control and data acquisition) system by transmitting telemetry data to ...

(RTU) that time-tagged events to the nearest millisecond, and now there are also other RTUs with this capability.

Digital protective relay In utility and industrial electric power transmission and distribution systems, a numerical relay is a computer-based system with software-based protection algorithms for the detection of electrical faults. Such relays are also termed as microp ...

s and some PLCs now also include time-tagging to the nearest millisecond; SCADA systems that incorporate these devices provide SER functions without a dedicated SER device.

References

Recording devices {{Comp-hardware-stub

See also

References