RCDs in welding systems

 Unplanned shutdowns of parts of the installation lead to production losses and equipment damage, endanger process reliability and the quality of the goods to be produced. It is therefore important to use suitable protective devices to interrupt the power supply only in the event of actually existing fault currents. Furthermore, incipient residual currents should be detected at an early stage. Only those who keep an eye on their electrical installation can react in time without the protective device switching off. The high currents and/or high voltages generated during resistance welding often mean that conventional RCDs/residual current devices (such as RCCB, RCBO, CBR) cannot be used.

The short, pulsed and extremely high load currents and the system-related high-frequency leakage currents lead to false tripping and thus to unnecessary interruptions. Furthermore, conventional RCD solutions cannot be optimally adjusted to the installation.

You gain flexibility. Modular residual current devices (MRCD) from Bender can be fully adapted to your application. Not only can the size of the external measuring current transformer be selected according to the conductor cross sections and the load current, but also can response values, response times, relay behaviour, frequency response etc. be individually adjusted to your installation.

False tripping is avoided. Due to the very precise measurements and the resulting much smaller tolerance range during tripping, your resistance welding system remains available for longer. Conventional RCD solutions can already trip at 50 % of the response value, the Bender MRCD trips at 65 % at the earliest, normally only at about 85 %. 

False tripping caused by external influences such as high load currents from nearby cables are reduced by the optionally available magnetically shielded measuring current transformers. The MRCD from Bender also offers an adjustable filter function for frequency ranges and allows you to use existing circuit breakers.

• High flexibility
• No false tripping
• Optimally adjusted to the special requirements of the welding application (insensitive to pulsed, very high currents with many different frequency components)
• Comprehensive electrical safety for man and machine
• Increased protection against indirect contact
• Very precise measurements and therefore no tripping before reaching approx. 85 % of the response value