07-11-2018 | | By Nnamdi Anyadike
The market for advanced surge protection devices (SPDs) is growing rapidly as vendors look to increase the safety of electrical systems. A report from Global Market Insights, Inc. released in October expects the global circuit breakers market to exceed $21billion by 2024. This increase is based on a rise in demand for circuit breakers in the refurbishment of ageing transmission networks. A Research and Markets report, meanwhile, projects a 5.33% CAGR rise in the medium voltage (MV) protection relay market, from an estimated $860 million in 2018 to $1,115 million by 2023.
One of the newer circuit breaker devices that is now on the market is the ground fault circuit interrupter, or GFCI. This device constantly monitors the current in a circuit's neutral and live wires although it is designed primarily to protect people from an electrical shock, rather than prevent damage to an individual building's wiring.
Unlike a fuse in the home, the GFCI is integrated into the outlet itself. It monitors the amount of current flowing from live to neutral and if there is any imbalance, it trips the circuit. The device can sense a mismatch as small as 4 or 5 milliamps, and it can react as quickly as one-thirtieth of a second.
Another technology that is coming to the fore is ACI (Advanced Circuit Interruption). Unlike with conventional fuses and circuit breakers, ACI allows for normal operation by offering voltage protection during high current surges. DEHN & SÖHNE GmbH & Co. KG the Nuremburg, Germany based family-owned electrical engineering company said, “The constant availability of electrical systems is a must. An interruption of the power supply or a failure of equipment is unthinkable.”
In October, the company showcased its new DEHNguard with ACI technology. The galvanic isolation by the ACI unit is designed to ensure a leak-free operation and a high temporary over voltage (TOV)-resistance. With an ACI arrester, no leakage currents occur thereby helping to prevent premature ageing of the protective devices.
Conventional solutions with fuse or circuit breaker are not – according to the company - ideal for SPDs. “High surge current during normal operation means high necessary tripping currents in the event of a fault, when the upstream fuse must switch off,” it says. It describes ACI technology as the next ‘evolutionary stage’ for the protection of an SPD, which will also help to save time, space and material, and thus costs.
One sector where over-current protection devices are increasing in demand is the military. Writing in Military Embedded Systems, Karl Kitts Director of Development Engineering for High Performance Relays at TE Connectivity, said that while a common way to protect high-power circuits from over-currents is to use bimetal-based circuit breakers that rely on thermal trip elements electrical systems engineers now have a smarter option: power contactors that incorporate integrated electronic current sensing technology.
These so-called smart connectors - based on the Hall Effect (HE) principle that enables output voltage to be varied in response to a magnetic field - provide at least twice the accuracy in trip setting over mechanical circuit breakers. They can also be exercised through built-in tests to simulate fault events to ensure they will perform as expected if a system fault occurs.
Among the other numerous advantages of Hall effect sensors are their ability to work with direct or alternating current, high accuracy, high dynamic performance, high overload capacities, high reliability, and built-in ambient-temperature compensation, unlike with conventional thermal breakers. “Similar to circuit breakers, smart contactor trip times can be adjusted according to the severity of the fault,” said Kitts. Although lengthy trip times may suffice for near-normal current levels, much larger faults require trip times of less than 0.015 second.
HE sensors, said Kitts, are also moving from, “responsive protection to insightful prediction.” He continued, “Data about the state of the contactor itself can be gathered and analyzed using microcontroller-based electronics. This information can go beyond basic trip circuit response history. Real-time operation can be monitored to identify trends and changes, enabling intelligent prediction of problems and proactive responses to maintain the health of the contactor.”
A raft of next generation sensors, based on the HE principle are about to come on to the market. At an end-November exhibition in Nuremburg, the US based Sensata Technologies, an industrial technology company and a leading provider of sensors, will showcase an array of new products including its very latest switches, Crydom relays, circuit breakers and electrical protection devices. Its SIL3/PLe-rated functional safety encoders that feature digital and sine/cosine analogue electronic output options, in addition to a new HE sensor with IO link, will also be on display.
These sensors will join HE products that are already available on the market from companies such as Siemens, ABB Ltd., Eaton Corp. Plc, Schneider Electric SE, General Electric Company (U.S.), Texas Instruments Inc.
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