Trust Automation, Inc. TA333 High Power Linear Servo Amplifier
10-Apr-09
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2.4 TA333 Safe Operating Area Curve (SOA)
The TA333 features a micro processor that constantly monitors the operating conditions on the
amplifier to prevent damage. This processor continuously calculates the dissipated wattage and sets a
fault threshold based on heatsink temperature, supply voltage, and motor current. The formulas for
calculated limits are current, wattage and temperature.
Current Limit
For currents that result in a dissipation wattage below 600W, the processor limits the time
logarithmically from infinite time at 6A down to 500ms at 25A. (See current vs. time graph).
Wattage Limit
If the resulting dissipation wattage exceeds 600W, the time to fault is much shorter as it is now
operating in the “knee” of the SOA curve. (See wattage vs. time graph).
Temperature Limit
The microprocessor takes into account the heatsink temperature when calculating the wattage time
limit. Time to fault is de-rated at about 15ms per 20°C rise. (See temp vs. time for an example at
876W). If the heatsink temperature exceeds 70°C FAULT is generated, and at 90°C the drive will
shutdown.
Figure 8 – TA333 SOA Curve
