Download the industry`s first combined rocker switch and CBE (circuit

October 2009
D1010/ETA
New rail-mounted double-pole electronic circuit breaker
E-T-A Circuit Breakers, quality designer and manufacturer of a broad range of electromechanical and electronic products for circuit protection, has introduced a new railmounted electronic circuit breaker, the E-T-A ESS22-T. Compliant with the machinery
safety standard EN60204-1 and particularly useful in process control, the steel industry
and power plant technology, it offers selective disconnection and double-pole physical
isolation of loads, only disconnecting faulty load circuits in the event of an overload or
short circuit.
The E-T-A ESS22-T provides electronic overcurrent protection for ungrounded 24V DC
power supply systems and comes with a choice of eight current ratings from 0.5A to 10A.
It responds fast enough to an overload or a short circuit to ensure stability of the 24V
control voltage for the other loads, such as PLCs, control systems and bus couplers, to
prevent stoppages of the entire automation system.
Short circuit currents are limited to around 1.4 times the rated current and the faulty load
is disconnected after approximately 100ms. Inrush peaks however, from switching on
capacitive loads up to 20,000 microF for example, are tolerated, thus avoiding nuisance
interrupts. In the event of an overload, the electronic circuit breaker will disconnect at
typically 1.1 times the rated current after 3 seconds.
The type ESS22-T can be snapped easily onto symmetrical rails, and, with a width of just
22.5mm and height/depth of 90mm, it ensures space saving in compact control cabinets.
Status indication of the connected load circuit is provided by a multicolour LED and the
condition of the ON/OFF switch. In the event of a failure, two physically isolated ‘make
and break’ contacts provide failure signalisation to a control system. The load circuit can
be re-set using the manual ON/OFF switch, a switch which can also be used during
maintenance.
For processes powered by 24V DC power supplies without circuits protected by a device
such as the ESS22-T, an overload in a single circuit will cause the power supply to shut
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D1010/ETA
down the output to all the circuits it supplies. On recovery it may go into ‘hiccup’ mode.
Costly downtime, scrap and even danger to personnel may result. Traditional protection
solutions do not provide the answer. Circuit breakers with fast operating characteristics
would be likely to cause nuisance trips during current peaks and switching on of
capacitive loads. On the other hand MCBs are too slow, and neither delayed operation,
nor high-performance, circuit breakers will respond adequately in this situation to
overcurrents. The power supply will therefore switch off completely, bringing all connected
loads, i.e. the entire system, to a standstill.
www.e-t-a.co.uk offers further information on E-T-A and its products.
- ENDS Notes to editor
E-T-A designs and manufactures a broad range of electro-mechanical and electronic
products for circuit protection, control and instrumentation, including the world’s largest
range of circuit breakers for equipment (CBEs). E-T-A equipment is specified and
installed by a wide variety of industrial OEMs and end-users, with key markets including
air, sea and land transport, process control, computers and communications, medical
equipment, domestic appliances, machine tools and robotics.
E-T-A is an international company with headquarters in Altdorf, Germany and production
facilities in several other countries, together with marketing, sales and technical
operations throughout the industrial world. Its European, North American and Far Eastern
markets are served by some 1,500 employees.
The World Wide Web site www.e-t-a.co.uk offers further information on E-T-A and its
products.
Press enquiries:
Terry Hilder, Pathway PR
Surrey Technology Centre, 40 Occam Road, Guildford, Surrey GU2 7YG, UK.
Tel: 01483 688450. Fax: 01483 688455. e-mail: [email protected]
Reader enquiries:
Gillian Dennis, E-T-A Circuit Breakers Ltd
Telford Close, Aylesbury, Bucks. HP19 8DG, UK.
Tel: 01296 420336. Fax: 01296 488497. e-mail: [email protected]
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