Like a diseased body, a defective portable power system will present symptoms. A Portal Power Distribution Technician, like a physician, must not only be able to recognize the symptoms but also have the analytic tools required to diagnose the problem and arrive at a cure. In this workshop, we learn how to recognize and treat the symptoms of a resistive neutral. A resistive neutral occurs when the system neutral has a high impedance. Good electrical connections have extremely low impedance (much less than an ohm), but a resistive neutral has an intermediate impedance (more than 3 Ω). Its impedance is low enough to conduct electricity, but too high to conduct it well. A resistive neutral will cause phase voltages to float, HMI ballasts not to strike, and possibly even cause a generator to fail.
Students should bring their digital multi- and clamp meters and a WIFI-compatible laptop (cellular phones will work but not ideal).
Example of Resistive Neutrals (Case Study)
The Scientific Method
Unbalanced Phase Voltages and their causes
Open Neutrals
Resistive Neutrals
VNeg
How to mitigate the effects of a resistive neutral
Load Balancing
Sources of resistance in a system neutral
Loose Connections
Corrosion
Damaged Cable
Ways to prevent cable damage
How to mitigate the effects of a resistive neutral (cont.)
Oversizing Cable
Paralleling Feeders
Isolating resistance in energized systems
Safe Metering Practices
Isolating resistance in un-energized systems
Details
Language: English
Format: In-person, Virtual
Length: 8 hours
Trainer
Guy Holt, IATSE Local 481
Location: Boston, MA
Guy Holt is a 28-year veteran of IATSE Local 481 and author of over twenty articles for Protocol magazine on power generation, quality, and distribution in motion picture production. Guy has served as Gaffer, Rigging Gaffer, and Generator Operator on numerous film and television productions.