Uninterruptible Power Supplies and Standby Power Systems
Written by two experienced engineers, this book covers rotary UPS systems and battery selection, and offers complete, up-to-date guidance on design, installation, operation, and maintenance.
TABLE OF CONTENTS Uninterruptible Power Supplies and Standby Power Systems
Voltage and Frequency Performance Classes for Diesel Engine Driven Sets
Specification ISO 8528 includes four performance classes for diesel engine driven generating sets, the details of which appear in Table 1.1. Other performance classes are available, such as ISO 3046 (BS 5514) for speed governing and BS EN 60034 for voltage control but are not reproduced here.
Modes of Control
There are three modes of control which may be used in connection with speed governors and voltage regulators. The error is the basic feedback signal and is the difference between the measured value and the desired value.
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Proportional control is the basic mode. Within a proportional band feedback is applied which is proportional to, and tends to reduce, the error. This form of control can achieve a stable state within the proportional band but there will be a deviation from the desired value, known as the offset.
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Integral control modifies the proportional feedback signal by adding to it a signal which has a rate of change proportional to the error, and attempts to nullify the offset. Adding integral to proportional control increases the accuracy at the expense of increasing the overall response time.
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Derivative control modifies the feedback signal by adding to it a signal which is proportional to the rate of change of the error. Adding derivative control to proportional plus integral control decreases the overall response time.
The initial letters P, I, and D are often used when referring to these modes of control. The proportional mode...
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