Copper losses

The declared efficiency and power factor of a motor are affected by its loading. Irrespective of the load, no-load losses as well as the reactive component of the motor remain constant. The useful stator current, i.e. the phase current minus the no-load current of a normal induction motor, has a power factor as high as 0.9-0.95. But because of the magnetizing current, the p.f. of the motor does not generally exceed 0.8-0.85 at full load. Thus, at loads lower than rated, the magnetizing current remaining the same, the power factor of the motor decreases sharply. The efficiency, however, remains practically constant for up to nearly 70% of load in view of the fact that maximum efficiency occurs at a load when copper losses (f R) are equal to the no-load losses. Table 1.9 shows an approximate variation in the power factor and efficiency with the load. From the various tests conducted on different types and sizes of motors, it has been established that the... 

Rotor copper loss = 3 V( /j/W, watts Motor output = 3 V, Ph watts AB is known as the output line, since the output is measured above this. 

Calculate the no-load stator copper loss watts. 

Subtract the no-load stator copper loss from the stator input power at no-load, i.e. (P ( - i R ). This is the net no-load loss made up of core, friction, windage and stray losses. 

Add the net no-load loss and stator copper loss on load and subtract their sum from the stator input power measured on load. The remainder is the power input to the rotor. 

Calculate the rotor copper loss (input to the rotor x percentage slip on load)... 

Subtract this rotor copper loss from the rotor input. 

As a check, add together the net no-load loss, the stator copper loss on load, the rotor copper loss on load and stray loss to give the total losses (total fixed loss plus load loss) ... 

The same theory would apply as diseiissed above in the case of two generators. Since there is no variation in the power input to PM, the output of generator G will remain the same, except for the marginal variation in the copper losses as noted etirlier ... 

Loss of copper. Solutions and crystals of ceruloplasmin that have been allowed to stand for several weeks partially lose their blue color and this may indicate changes in copper oxidation state and/or loss of copper. A series of experiments are required to determine whether any copper loss is site preferential and how this is affected by anionic inhibitors. 

One of the main problems associated with beneficiation of the Kolwezi siliceous ore is the production of malachite and pseudomalachte slimes that have a relatively low flotation rate. Most of the copper losses occurring in the plant are in the -15 pm fraction. Experimental testwork conducted with a different palm oil emulsifier indicated that copper recovery from the fine fraction can be significantly improved with the use of petroleum sulphonate (Petrosol 845) as the emulsifier [21] for palm oil. Significant improvement in copper recovery was realized in the fine fractions with the use of palm oil emulsified with Petrosol 845. 

As shown in the bottom row of Fig. 18, the advantages of the dimer of dimers model over the heterodimer model are several (1) There is no need to disrupt the very stable SODl homodimer. (2) Instead of the 40-A movement by the CXC motif of domain 3 to the copper-binding site of SOD 1, the distance would be much shorter, minimizing the possibility of copper loss. The movement of copper from lower (MXCXXC) to higher (Cu,ZnSOD) affinity sites via domain 3 would occur in a very confined space and in a rapid time due to this proximity. (3) Copper can be delivered to both copper sites of dimeric SOD 1 simultaneously. (4) Practically... 

There is a positive correlation between high copper loss from an intrauterine contraceptive device and the development of menorrhagia or pathological lesions, such as cervical dysplasia and endometrial cjdopathol-ogy (14). Evidence of endometrial carcinoma was not found in endometrial aspirates from 189 women who had used Copper-T-200 devices for 1-10 years, but five cases of endometrial hyperplasia (2.67%) were encountered in women in the series, all of whom had worn... 

Engineer AD, Misra JS, Tandon P. Copper loss cyto-pathological changes associated with copper lUD use. Indian J Med Res 1983 78 42-8. 

Apart from prosthetic copper loss due to environmental factors, coordination site structural changes that are detectable by spectroscopic techniques can occur. These changes are discussed later in the section on spectroscopic properties. 

Between 0.5 and 2.0 mg of copper per day is excreted via bile into feces. Patients with cholestatic jaundice or other forms of hver dysfunction are therefore at risk of copper accumulation caused by failure of excretion. Copper losses in urine and sweat are <3% of dietary intalce. Urine copper output is normally less than 60pg/day. 

The dc level of the inductor current (largely) determines the I2R losses in the copper windings ( copper loss ). However, the final temperature of the inductor is also affected by another term — the core loss — that occurs inside the magnetic material (core) of the inductor. Core loss is, to a first approximation, determined only by the ac (swinging)... 

---