| Questions |
| Questions |
| 1 | Boucherot's teorem allows to calculate triphase power starting with: | ||
| A) | Phase tensions | ||
| B) | Line tensions | ||
| C) | Monophase power | ||
| D) | Line currents | ||
| 2 | In a symmetrical and balanced triphase system, the apparent triphase power is calculated by the product: | ||
| A) | √3 V I with V and I efficient current and tension values ) | ||
| B) | √2 V I (with V and I efficient current and tension values ) | ||
| C) | V I (with V and I efficient current and tension values ) | ||
| D) | V I cos φ (with V and I efficient current and tension values φ the power factor ) | ||
| 3 | In a symmetrical and balanced triphase system, active triphase power is calculated by the product: | ||
| A) | √3 V I with V and I efficient current and tension values ) | ||
| B) | √2 V I (with V and I efficient current and tension values ) | ||
| C) | √3 V I sen φ (with V and I efficient current and tension values and φ the power factor) | ||
| D) | √3 V I cos φ (with V and I efficient current and tension values and φ the power factor) | ||
| 4 | In a symmetrical and balanced triphase system, reactive triphase power is calculated by the product: | ||
| A) | √3 V I with V and I efficient current and tension values ) | ||
| B) | √2 V I (with V and I efficient current and tension values ) | ||
| C) | √3 V I sen φ (with V and I efficient current and tension values and φ the power factor) | ||
| D) | √3 V I cos φ (with V and I efficient current and tension values and φ the power factor) | ||
| 5 | If an equal 3 impedence module connected to a star is worth 3 ohm, the module of one of the three impedences connected to equal triangles is worth: | ||
| A) | 3 ohm | ||
| B) | 1 ohm | ||
| C) | 9 ohm | ||
| D) | 27 ohm | ||
| 6 | An impedence phase is characterised by only reactance capacity, is worth: | ||
| A) | −π/2 | ||
| B) | π/2 | ||
| C) | −2/3π | ||
| D) | 2/3π | ||
| 7 | An impedence phase is characterised by only an inductive reactance capacity, is worth: | ||
| A) | −π/2 | ||
| B) | π/2 | ||
| C) | −2/3π | ||
| D) | 2/3π | ||
| 8 | In a symmetrical and balanced triphase system, instant power: | ||
| A) | Varies with the sinusoidal law with a frequency equal to the generators | ||
| B) | Varies with the sinusoidal law with a frequency double to the generators | ||
| C) | Has an average value of null over the period | ||
| D) | Is constant over time | ||
| 9 | Instant power absorbed by a balanced triphase load fed by a trio of symmetrical tensions is calculated by the product: | ||
| A) | 3 E I (where E is the phase tension and I the absorbed current) | ||
| B) | 3 E I cos φ (where E is the phase tension and, I the absorbed current and φ the power factor) | ||
| C) | 3 E I cos (ωt) (where E is the phase tension and I the absorbed current) | ||
| D) | 3 E I cos (ωt+φ) (where E is the phase tension and , I the absorbed current and φ the power factor) | ||
| 10 | The alternative components of instant power absorbed by a trio of balanced impedences fed by a trio of symmetrical tensions: | ||
| A) | Have a value which dipends on impedences | ||
| B) | Cancel | ||
| C) | Have a frequency equale to that of generators | ||
| D) | Have a variable average value over the period | ||