List three general procedures for dealing with harmonics.
What will be an ideal response?
1. In a three-phase, four-wire system, the 60-Hz part of the neutral current can be reduced by balancing the current on the phase conductors. If all phases have equal current flow, the neutral current would be zero.
2. If triplen harmonics are present on the neutral conductor, harmonic filters can be added at the load. These filters can help reduce the amount of harmonics on the line.
3. Pull extra neutral conductors. The ideal situation would be to use a separate neutral for each phase, instead of using a shared neutral.
4. Install a larger neutral conductor. If it is impractical to supply a separate neutral conductor for each phase, increase the size of the common neutral.
5. Derate or reduce the amount of load on the transformer. Harmonic problems generally involve overheating of the transformer. In many instances it is necessary to
derate the transformer to a point that it can handle the extra current caused by the harmonic distortion. When this is done, it is generally necessary to add a second transformer and divide the load between the two.
You might also like to view...
Technician A says fuel that has low volatility can cause a buildup of deposits in the combustion chamber. Technician B says liquid gasoline will not burn. Who is correct?
A. Technician A B. Technician B C. Both A and B D. Neither A nor B
You have a gully forming in the back of your lot. You hired someone at $120 per hour for 5 hours and 15 minutes to level the ground so the water will travel over a larger area. You planted 25 feet of hedge 10 inches apart at the lower edge. You sodded a rectangular area 30 feet by 75 feet. The sod used is 24 inches by 60 inches.
a. How many plants were needed? b. What did it cost to level the gully? c. How many pieces of sod were used?
F&D Elevator received two loads of corn: 895 bushels with 22 percent moisture and 850bushels with 18.5 percent moisture. F&D Elevator paid $6.70 per bushel for corn with 15.5 percent moisture or less. F&D Elevator has a 3.3 percent dockage for each point over 15.5 percent moisture. One bushel of dry corn (15.5 percent moisture) equals 56 pounds.
a. What did F&D Elevator pay for the 895 bushels? b. What did F&D Elevator pay for the 850 bushels? c. How many bushels of dry corn did F&D Elevator actually buy? (Note: Do not forget the shrinkage.)
What is a vent connector?
A) Vent connector is simply another name for vent. B) The vent connector is the collar on the gas appliance where the vent pipe connects. C) The vent connector is the pipe running from the furnace to the vent. D) A vent connector is used to join two pieces of vent pipe.