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kislay2005
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Can the power factor of an electrical system ever be greater than 1? if yes.. then when and how?
accurate.wate said:Ok, well, This question is on the TCEQ A-Operator exam:
5. You have a newly installed deep well vertical turbine pump with centrifugal motor driver with a guaranteed overall efficiency of at least 74%. The pump is pumping 500 gpm from a well with a 60-foot static level and a specific capacity of 12.5 into a 180-foot elevated tank. The pump driver is a three-phase motor with a power factor of 1.05. It is drawing 43 amps on a 480 volt service. A gauge 5 feet above ground level at the tank site is reading 69 psi. The total head loss is 8%. What is the actual overall efficiency?
A. 95.2%
B. 84.7%
C. 74.1%
D. 71.7%
E. 60.3%
It states that the power factor is 1.05! Can you explain that?
Ug, looks like some cross discipline language mangling in play here. http://en.wikipedia.org/wiki/Power_factor" is always one or less.m.s.j said:Yes it is always greater than 1, indeed he says about power factor margin which means the relation of rated power of electrical driver and its related mechanical load.
PF = Rated power of electrical motor / Required maximum mechanical power
Of course when considering centrifugal machines it is important to base the motor rating on the ‘end of curve’ condition of the driven machine, because in practice the machine may need to run at this extreme condition for a reasonably long period of time. This condition is generally defined as 125% of the capacity of the machine at the maximum working efficiency point on the ‘head-flow’ curve for the designed shaft speed.
Yes, power factor can be greater than 1 in certain scenarios. This is known as leading power factor and occurs when the load is capacitive, meaning it consumes reactive power instead of producing it. Examples of capacitive loads include fluorescent lights, motors, and transformers.
A power factor greater than 1 is caused by a phase shift between the voltage and current in an electric circuit. This phase shift occurs when the load is capacitive, resulting in a leading power factor. It can also be caused by the presence of harmonics in the electrical system.
In most cases, a power factor greater than 1 is not desirable as it can result in inefficient use of electricity and higher energy costs. However, in some industrial applications, leading power factor can be beneficial as it can improve the efficiency of certain equipment and reduce the overall energy consumption.
A power factor greater than 1 can be corrected by installing power factor correction equipment, such as capacitors, to compensate for the capacitive load. This will bring the power factor closer to 1 and improve the overall efficiency of the electrical system.
Yes, there are some potential risks associated with a power factor greater than 1. These include overloading of the electrical system, increased voltage stress on equipment, and potential damage to sensitive devices. It is important to monitor and correct power factor to prevent these risks from occurring.