Weidmüller WAVEGuard

Weidmüller’s WAVEGuard is a innovative concept to protect circuits. Many applications in system and control modules require a power pack output which is frequently divided across more than ten circuits. In compliance with IEC 60204-1 an appropriate individual protection is required. However, the problem with using regulated power packs, is the current limitation. Due to their technical properties, switched-mode power supplies either provide no or only a limited dynamic output current. Even automatic circuit breakers with the characteristics C, B or Z do not solve these problems in principle, they require a tripping current of between 2.5 and 15 times their nominal current. So far all efforts have failed: switched-mode power supplies cannot reliably trip conventional automatic circuit breakers and fusible cut-outs. The electronic fuse rectifies the insufficient tripping capability of automatic circuit breakers. It is made up of two fuse elements in series: a conventional fusible cut-out and an electronic fuse. For a mains current of 24 Vdc, the critical nominal currents 1.6 A, 3.15 A , 6.3 A and 8 A are realized. WAVEGuard is the only device available that selectively protects circuits which are supplied by switched-mode power supplies dynamically and statically. WAVEGuard accelerates error searching in the secondary circuit and reduces repair and maintenance costs.

The design is such that the fusible cut-out - it complies with the prescribed standards - is tripped only if the electronic element fails. There are no standards available for electronic fuses as part of devices, therefore they cannot be used by themselves. The electronic fuses use fast semi-conductors. The trip current is set during the manufacturing process using a resistance combination to be precisely between 0.5...8 A. The current supply is interrupted as the fuse records the current flowing through it and the semi-conductor is switched off when the pre-set highest admissible value has been reached. Switching off only takes milli-seconds. The highest admissible static value is 100% of the nominal fuse value, in addition, it also has a dynamic value. Short current peaks are passed on to the power load, in the case of a short-circuit the fuse is triggered quickly and reliably. The line-side fuse only reacts in the case of the electronic part failing. A total of six connections are available. Users can choose between modules with the tried and tested screw or tension clamp connections: Main fuse branch 24 Vdc, 0 V potential, reset input and signal contact.

WAVEGuard has a slide switch integrated into its front to switch the fuse element on and off. If the fuse has been tripped erroneously, after the error has been rectified, the sliding switch is pushed into the OFF position for ten seconds and then pushed back into the ON position. Remote switching off is also possible: To do this, the reset input must be connected with a voltage impulse, the load circuit is made with a decreasing pulse edge. For safety reasons, a cyclical auto-reset has not been incorporated.

Light emitting diodes on the front of the module indicate the switching state of the fuse. If the LED is green, it is OK, if the LED is red, the fuse has been tripped. Trouble shooting is also facilitated by the potential free signal contact: the opener (max. 50 V/0.1 A) has only been designed for small voltages, mains voltage uses an external relay. The signalling delay is 3.5 milli-seconds.

WAVEGuard is incorporated in the WAVEBOX housing. Inductive loads can be connected externally using free-wheeling diodes. The electronic fuse WAVEGuard is not suitable for use with batteries – feedback. The innovative product complies with CE standards, certification in compliance with UL/ CSA is under way.

Weidmüller completes its fuse designs with a product range of switched-mode power supplies.