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This report by John Kueck investigates the effects of voltage sag and recovery on motor protection and control mechanisms. It categorizes various motor types based on the Composite Load Model and evaluates their protective behavior. Key findings highlight that the dropout voltage of relays and contactors significantly influences motor control equipment. The report also covers the implications for various motor specifications, such as adjustable speed drives and HVAC components, discussing the interaction with motor torque and performance during voltage fluctuations.
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Preparing Summary PaperProtection and Controls for Motor Loads Under Voltage Sag and Recovery John Kueck
Summary of Findings • The influence of voltage sag and recovery on typical motor protection and controls. • This report breaks down each Composite Load Model class into motor types and provides an overview of protection behavior for each type • Also, the actual dropout point of much motor control and protective equipment probably depends more on the drop out voltage of relays and contactors, especially the ubiquitous ice cube relay.
Other Issues to be Summarized • Contactors and relays – to be tested soon at SCE, drop out already known. The combined effect with motor protection will be discussed. • Discussion of motor speed torque curves, pull up torque and load torque • Air conditioner stall as a function of ambient temperature • Point on wave – John Undril
Overview and Estimates of Response for the following Protection and Control Types • Adjustable Speed Drives • Large motors over 250 HP • Three phase motors under 250 HP, NEMA Design B • Single phase air conditioners • Single phase appliances • Rooftop air conditioners • Chiller motors larger than 250 HP
