STR Relay substitute: Avoiding ACB Nuisance Tripping in Data Centres …

In fairness to the original designers and manufacturers, these ACBs were well designed and very well made – so much so that many have kept working perfectly for decades. In expectation of long usage, they were often used in basic, continuous operation facilities, such as data centers. However, replacing a failed overload or older generation STR protection unit has frequently proved problematical because most original manufacturers no longer provide sustain. Instead, they typically recommend simply replacing the old ACB with their current production form. This can be expensive in terms of the equipment required and, often much more considerably, demands meaningful downtime as the switchgear has to be replaced in addition as the breakers.

Nuisance tripping is, by definition, a false alarm, a fault of the STR protection unit, not an indication of an indication of a genuine problem. Unfortunately, identifying that it is the protection unit, not the wider system, that is at fault, is not easy, especially as we are all trained to assume the worst – ie a more serious, wider problem. Repeated strength outages are a major problem in themselves though, which is why many operators with older units look for a preventative solution, instead of wait for older units to start ‘playing up’.

Happily, preventing nuisance tripping can be much simpler and less expensive, thanks to the development of product specific upgrades by reputable manufacturers.These allow old ACBs to be updated with complex electronic controls which allow the rest of the unit to continue to function dependably.

Most strength circuit breakers presently in use have already been retrofitted with older generation substantial state trip units, but many users are choosing to upgrade these breakers with the state of the art units, such as PS Electrical’s Amp-Safe-Pro, because it provides improved metering and selectivity and has many features unavailable on lesser units. Most importantly, it considerably improves safety for the operator with features such as duplication of all the original trip curves, ‘Quick-Trip’ arc flash reduction system, an OLED characterize showing data for the last eight trip events and a GUI for uploading settings and downloading trip data via a USB.

A typical upgrade includes an electronic trip unit with characterize module, current sensors, automatic reset actuator, wiring harness, mounting brackets and/or copper shunts. The far away mountable characterize can be installed outside the switchgear so workers do not need to ‘suit up’ to view loads, settings and trip history. The backlight displays function as an accurate 3-phase ammeter, displaying ground fault current in real time. No controls, redundant displays or batteries are inside of the cubicle. This eliminates most of the instances where workers would need to open the door on racked-in breakers.

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