E-T-A announces rail-mounted circuit breaker

Compliant with the machinery safety standard EN60204-1 and particularly useful in process control, the steel industry and power plant technology, the device 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 over-current 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 three seconds.

The type ESS22-T can be snapped onto symmetrical rails and with a width of 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 signals to a control system.

The load circuit can be reset using the manual on/off switch; the switch 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 down the output to all the circuits it supplies.