Podcast
Questions and Answers
What is the date of the maintenance on ground or replace?
What is the date of the maintenance on ground or replace?
- February 8, 2001
- January 7, 2001
- January 9, 2001
- January 8, 2001 (correct)
What is the temperature mentioned in the ambient conditions?
What is the temperature mentioned in the ambient conditions?
- 75 °F
- 85 °F
- 80 °F
- 83 °F (correct)
What is the name of the engineer mentioned in the report?
What is the name of the engineer mentioned in the report?
- James Johnson
- John Smith
- Harry Tittel, E.E. (correct)
- Michael Brown
What is the test method used in the earth ground test?
What is the test method used in the earth ground test?
What is the address of Florida Electrical Resources?
What is the address of Florida Electrical Resources?
What is the phone number of Florida Electrical Resources?
What is the phone number of Florida Electrical Resources?
What is the typical range of ground fault current in an electrical system?
What is the typical range of ground fault current in an electrical system?
What is the primary purpose of a system ground in an electrical circuit?
What is the primary purpose of a system ground in an electrical circuit?
What is the characteristic of a high resistance grounded system?
What is the characteristic of a high resistance grounded system?
What is the benefit of high resistance grounding in terms of transient overvoltages?
What is the benefit of high resistance grounding in terms of transient overvoltages?
What is the primary application of high resistance grounding?
What is the primary application of high resistance grounding?
What is the purpose of a maintenance ground?
What is the purpose of a maintenance ground?
What is unique about electronic and computer grounds?
What is unique about electronic and computer grounds?
What is the benefit of system grounding in terms of motor insulation life?
What is the benefit of system grounding in terms of motor insulation life?
What is the typical resistivity of clay-sand-gravel mixtures?
What is the typical resistivity of clay-sand-gravel mixtures?
Which type of soil has the highest resistivity?
Which type of soil has the highest resistivity?
What is the characteristic of low resistivity soils?
What is the characteristic of low resistivity soils?
What is the typical resistivity of fine sandy or silty clays, silty clays, lean clays?
What is the typical resistivity of fine sandy or silty clays, silty clays, lean clays?
Which type of soil has a resistivity of 55 ohm-cm?
Which type of soil has a resistivity of 55 ohm-cm?
What is the characteristic of marls?
What is the characteristic of marls?
What is the typical resistivity of gravel, gravel-sand mixtures?
What is the typical resistivity of gravel, gravel-sand mixtures?
What is the characteristic of decomposed granites, gneisses, etc.?
What is the characteristic of decomposed granites, gneisses, etc.?
What is the main characteristic of an ungrounded system?
What is the main characteristic of an ungrounded system?
What happens to the neutral potential of an ungrounded system with balanced loading?
What happens to the neutral potential of an ungrounded system with balanced loading?
What is a disadvantage of solidly grounded systems?
What is a disadvantage of solidly grounded systems?
What is the purpose of the grounding resistor in a low resistance grounded system?
What is the purpose of the grounding resistor in a low resistance grounded system?
What type of system is commonly used in low voltage distribution systems?
What type of system is commonly used in low voltage distribution systems?
What happens to the voltage on unfaulted phases during a fault in a solidly grounded system?
What happens to the voltage on unfaulted phases during a fault in a solidly grounded system?
Why is low resistance grounding not recommended for low voltage systems?
Why is low resistance grounding not recommended for low voltage systems?
What is an advantage of low resistance grounded systems?
What is an advantage of low resistance grounded systems?
What is the amperage reading recorded at the Stacker, Sorter, C-N-S Area?
What is the amperage reading recorded at the Stacker, Sorter, C-N-S Area?
What is the resistance recorded in the test results?
What is the resistance recorded in the test results?
What is the temperature recorded in the ambient conditions?
What is the temperature recorded in the ambient conditions?
What is the location of the test point?
What is the location of the test point?
What is the company name mentioned at the bottom of the page?
What is the company name mentioned at the bottom of the page?
What is the fax number of the company?
What is the fax number of the company?
What is the time of the test?
What is the time of the test?
What is the ground condition mentioned in the ambient conditions?
What is the ground condition mentioned in the ambient conditions?
Study Notes
Types of Grounding Systems
- Ungrounded system: capacitively coupled, neutral potential close to ground potential due to capacitance between phase conductors and ground, low ground fault current, very high voltages on unfaulted phases, sustained faults lead to system line-to-line voltages on unfaulted lines, insulation failure, and failure due to restrike ground faults.
Solidly Grounded System
- Neutral connected to ground without intentional impedance, large magnitude of current flow, aids in coordination, low initial cost, but stray currents may become a consequence, common in low voltage distribution systems, typically feeds to transformer primary with high side fuse protection, not preferred for industrial or commercial facilities due to high magnitude fault currents.
Low Resistance Grounded System
- Neutral connected to ground through a small resistance, limits fault current, size of grounding resistor selected to detect and clear faulted circuit, limits transient overvoltages during ground faults, not recommended for low voltage systems due to limited ground fault current, ground fault current typically in the 100-600 Amp range.
High Resistance Grounded System
- Neutral connected to ground through a resistive impedance, limits ground currents to a desired level, physically large resistor banks, very low ground fault current, typically under 10 Amps, special relaying methods utilized to detect and remove ground faults, typically applied to situations where it is essential to prevent unplanned outages, recent trend is to utilize high resistance grounding on 600 volt systems and lower.
Grounding Systems
- System grounds: connected to earth, provides a low impedance path for fault currents, improves ground fault coordination, ensures longer insulation life of motors, transformers, and other system components.
- Maintenance grounds: temporary ground, used for safe work practices.
- Electronic and computer grounds: equipment ground and system ground combined and applied in unity.
Earth Ground Test Report
- Earth ground test data: amperage reading, test results, notes, ground tested within parameters.
- Test point digital image and location representation.
- Test method: clamp on ground tester.
- Client/facility: client name.
- Engineer: Harry Tittel, E.E.
- Date: January 8, 2001.
- Ambient conditions: temperature, humidity, dry ground.
- Test results: ohms reading, notes.
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Description
This quiz covers the characteristics of ungrounded systems in electrical engineering, including capacitively coupling, neutral potential, and fault currents. It also explores the effects of sustained faults and insulation failures.
