OMICRON Magazine

Imagine this scenario: It’s a hot day, and John is on-site testing voltage transformers. He’s been working all morning injecting 1,400 V into the HV terminals of multiple VTs and taking secondary measurements with the junction box, relay terminals, and further downstream equipment. He’s been repeating these tests for hours using the Quick card function from the CPC 100. As he completes the last set of measurements, he walks back to the VT to disconnect the clamp but doesn’t realize that the CPC 100 is still outputting voltage. He comes into contact with the high voltage and receives a fatal shock. Mistakes like this happen very quickly because human senses can’t detect electrical hazards, and thus, they remain invisible. As with most accidents, multiple factors contribute to their occurrence. In this case, the five safety rules were violated, the red/green status lights of the CPC 100 wasn’t observed, and John had been performing dangerous tasks without a co-worker. He was likely fatigued after a long, hot day doing repetitive tests. At OMICRON, we strive to make the best products and continuously look for ways to improve our devices and related work. Safety is one of our highest priorities and we’re always introducing new features that reduce risks. We’re proud to announce the release of two new CPC 100 features contained in the latest version of the PTM 5.00 software: 2 kV-Timeout in Quick and Rapid Fault Sense (RFS). Considering its unique output characteristics, these features are tailored to address the specific working environment in which the CPC 100 is used. 2 kV-Timeout in Quick is easy to explain: The CPC 100 will terminate high voltage injection in the Quick-Test card after a 10-second default. This time limit can be user-defined and deactivated if required; it resets itself with every reboot. This may contribute to safety when a user is distracted and loses situational awareness. In a nutshell: RFS is an output supervisor that can detect output changes and initiate an immediate switch-off of the CPC 100. However, a little more information is required to describe how it works. The IEC TS 60479-2 Standard gives us a general idea of how fast the device must be switched off to lower the risk for heart fibrillation effectively. Assuming, for example, that there’s 1 Ampere of body current during an accident, it must switch off in less than one millisecond to keep the risk reasonably low. For comparison: Standard Residual Current Devices (RCDs) typically trip within a few tenths of a millisecond and require additional supervised circuits to be isolated from the ground. They’re too slow for high body currents, and many CPC 100 applications require a direct connection to the ground. So, we had to think differently. Building a system that can meet these requirements is an immense technical challenge. However, RFS may be capable of addressing this issue because it can detect faults within a few hundred microseconds. The output semiconductor amplifier is much faster than a physical relay so it can switch off the CPC 100 immediately. NEW SAFETY FEATURES THAT PTM 5.00 ADDS TO THE CPC 100 «Since they’re both software-based, virtually every CPC 100 can be updated immediately, free of charge. Stay safe!» 28