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In PQ News
Call of the Month for May 2025 Via the EPRI PQ Hotline, a PQ Knowledge funder conducted a power quality investigation for one of their industrial customers and found a contactor with a coil rated for both AC and DC voltages. The utility engineer recently attended a power quality training course and learned about voltage sag mitigation technologies that may be applied to relays, contactors, and motor starters with AC coils. The funder inquired whether contactors with AC/DC rated coils are sensitive to voltage sags, and if so, would the same voltage sag mitigation technologies apply. Figure 1 shows a NEMA Size 00 with a coil rated for AC voltage only and a contactor rated for AC or DC voltage.
Most Popular PQ Documents (Based on Clicks)
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P1 Update
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EPRI Industrial PQ Training Videos
As a follow-up to our Industrial Power Quality training classes, we have posted these complementary training videos to help solidify the concepts for both utility members and their customers. The top three are listed here.
Visualizing PQ Drive Parameters for Improved Voltage Sag Ride-Through 
This video demonstrates the voltage sag susceptibility of AC drive systems and how to improve the drive’s robustness through parameter changes.
Understanding PLC Voltage Sag Ride-through: AC and DC Powered Systems
This video demonstrates the differences in voltage sag ride-through between an AC powered PLC system and a DC Powered PLC system.
Power Conditioning to Enhance Control System Voltage Sag Ride-Through: The Constant-Voltage Transformer
This video shows how a CVT can be utilized to harden the voltage sag response of an automated control system.