Factories are electronic jungles in which microelectronic automation controls have a tough time surviving. Normal operation of factory machinery creates a constant background of electrical disturbances that increasingly cause malfunctions or failures. These problems are increasing because electronic systems have evolved in ways that have dramatically changed their power requirements. As semiconductor components become smaller and more dense, they become vulnerable to transient "noise" voltages that only a few years ago were considered insignificant. Transient, high frequency voltage differentials between line and neutral are referred to as normal mode noise. Semiconductor components begin to degrade at 10 volts normal-mode and are often destroyed at about 40 volts. Transient, high-frequency voltage differentials between line and ground are referred to as common-mode noise. Common-mode voltages as low as 5 volts can cause disruption because digital logic uses the safety ground as the zero-voltage reference point. Even small voltages confuse semiconductors and disrupt increasingly complex automated factory processes.
For today's automation controls, power protection devices must restrict high frequency noise pass-through to voltage levels that will not disrupt or degrade the semiconductors, while simultaneously transmitting current pulses with a minimum of impedance.
Automotive Case Study
American Axle
Maintaining Manufacturing
The Problem : "Communication Failure"
Communication lock-ups and erratic operation were interrupting the manufacturing process for American Axle. Since the equipment was protected by a typical UPS, the customer had a false sense of security as to what was at the root of the problem. The graph at right shows the UPS's output – transients passing through the UPS - which corresponded to a lock-up.
The Challenge : "LFOT"
LFOT – Low Frequency Oscillatory Transients of less than 3kHz were being generated within AA's manufacturing facility, common for this industry. Filtering out, and isolating against LFOT's is a challenge, as is properly defining the nature of the power quality disturbance.
The Solution : "4 Phased Methodology"
On Power conducted the necessary up-front monitoring, which included monitoring the output of the existing UPS, and other points of the power distribution to detect the nature LFOT problem. Step two involved the installation of a true, on-line UPS that can isolate against LFOT's and other power quality problems. On Power then monitored the input and output power of the new UPS, which showed clean power, and more importantly, no lock-ups or disruption to American Axle's business process.