Reliable switch of capacitive, inductive and high DC loads.
If special loads such as inductivities or high inrush currents are to be switched or monitored safely and reliably, you need individually tailored relay modules and solid-state relays. These customized solutions extend the service life of the switching element and, they can be installed in a space-saving cabinet thanks to optimized connection options.
Weidmüller provides special products for:
Reliably mastering destructive inrush currents.
Loads with a capacitive load share always place extreme demands on the switching contacts – regardless of the voltage type. This applies in particular for LED lamps. When switched on, they cause high-energy current peaks that can quickly reach more than 100 A and weld the contact.
But loads with capacitive components are not immediately recognizable every-where. They can also be hidden in components that are typically assigned to inductive loads - e.g. solenoid valves and contactors with an pre-circuitry to extend the input voltage range. In these pre-circuits capacitors can generate current peaks of up to 150 A when they are switched on. This can also lead to welding of the contacts or destruction of the output.
Optimal relay solutions for loads above 24 V DC
Switching relays can switch off only relatively small DC voltages and currents because the zero crossing for extinguishing the arc is missing here. The maximum DC current value is also dependent on the switching voltage and on design conditions such as contact spacing and contact opening speed.
In the case of undamped inductive DC loads, the energy stored in the inductive load can ignite a standing arc that passes the current through the open contacts. This causes extremely high contact wear, resulting in premature failures. Such high loads can be switched reliably if relay modules and solid-state relays specially designed for this application are used. These have, for example, built-in blow-out magnets or large contact openings, which significantly minimizes contact wear. In the following you will find special relay solutions for switching high DC voltages and currents.
Reliably break off arcs that cause wear
When switching solenoid valves and other inductive loads, arcs with voltage peaks of up to several thousand volts can occur. They are caused during the switching process by the energy stored in the coil and can destroy the contact by material vaporization and material migration. Intense arcing occurs when switching inductive DC loads. As a result, relay contacts are subjected to high stress and wear quickly. The use of power relays can reliably suppress the occurrence of such arcs. In addition, an external suppressor circuit is recommended. Arcing also occurs when switching inductive AC loads, but they usually extinguish themselves at the next zero crossing of the load current. The larger the switched inductive loads, the stronger the arcs that occur. In applications with inductive loads above 2 A, power relays should therefore be used instead of conventional signal relays. Otherwise, a significantly reduced service life of the contacts must be expected. On the following pages you will find special products for switching inductive loads above 2 A.
Special solutions for space- and time-saving installation
Optimizing wiring time and space requirements is becoming more and more important. Our variants with latching PE foot enable fast wiring of actuators where a PE contact is required. This eliminates the need for an additional PE terminal in the control cabinet. Our 1 NO ACT variants allow the use of a terminal on the relay socket for wiring the negative or neutral potential. In this way, the negative potential is bridged through to the connection provided for this purpose with the aid of a supply terminal in order to wire the actuators directly - without an additional terminal for the negative potential. On the following pages, we will introduce you to clever relay solutions that can save you a lot of space and time when wiring.
