The turns ratio of a transformer is defined as **the number of turns on its secondary divided by the number of turns on its primary**.

Terminals S1/S2 (k/l)

The connections of the primary winding are designated "K" and "L" or "P1" and "P2", and **the connections of the secondary winding** are designated "k" and "l" or "S1" and "S2". The polarity must be established such that the "flow direction of the energy" runs from K to L.

**P = V X I** . Here P is power in watts. V is voltage in volts. I is current in amps.

Transformer Turns Ratio Formula**The number of turns on the primary winding divided by the number of turns on the secondary coil** is the transformer turns ratio.

N/A

- Primary turns (n1) = Turns per volt(Tpv) * Primary voltage(V1)
- Secondary turns (n2) = Turns per volt(Tpv) * secondary voltage(V2) * 1.03 (Assume that there is 3% drop in transformer windings)
- The width of the tongue of laminations is approximately given by:-

To determine the required transformer VA, **multiply the secondary voltage by the required amperes**: For example, VA=Volts x Amperes or 28V x 1.2 amperes = 33.6 VA. To determine the maximum transformer current, divide the transformer VA by transformer secondary voltage.

K-factor is **a weighting of the harmonic load currents according to their effects on transformer heating**, as derived from ANSI/IEEE C57.110. The higher the K-factor, the greater the harmonic heating effects. There are many different loads such as computers, solid state devices and motors which cause a non linear load.

The CT ratio is **the ratio of primary current input to secondary current output at full load**. For example, a CT with a ratio of 300:5 is rated for 300 primary amps at full load and will produce 5 amps of secondary current when 300 amps flow through the primary.

**The transformer calculator uses the following formulas:**

- Single Phase Transformer Full-Load Current (Amps)= kVA × 1000 / V.
- Three Phase Transformer Full-Load Current (Amps) = kVA × 1000 / (1.732 × V)
- Turns Ratio = N
_{1}/ N_{2}= V_{1}/ V_{2}= I_{2}/ I_{1}

**Vp=−NpΔΦΔt** V p = − N p Δ Φ Δ t . This is known as the transformer equation, and it simply states that the ratio of the secondary to primary voltages in a transformer equals the ratio of the number of loops in their coils.

The primary voltages or high voltages (HV) is **11000 V = 11kV**. And the primary current on the high voltage (HV) side is 5.25 Amperes.**In simple words,**

- Transformer rating in kVA = 100 kVA.
- Primary Voltages = 11000 = 11kV.
- Primary Current = 5.25 A.
- Secondary Voltages = 415V.
- Secondary Current = 139.1 Amperes.

**The copper and iron are the two types of losses that occur in the transformer**. The copper loss depends on the current (ampere) flows through the windings of the transformer while the iron loss depends on the voltage (volts). i.e., the rating of the transformer is in kVA.

**Divide the number of secondary windings by the number of primary windings, and multiply the source voltage by this ratio**. This will give you the output voltage.

Windings and Wire

You now need to determine the number of turns that will be required for each secondary winding. The first step is to use formula **3 (N(s) = V(s) / V(p) x N(p))** to determine the turns for a perfect transformer. This number then needs to be increased to account for the losses in the coils.

According to Faraday's Law, you can calculate the voltage induced in the primary or secondary windings of the transformer by calculating **N x dΦ/dt**. This also explains why the transformer turns ratio of the voltage of one part of the transformer to the other is equal to the number of coils of one to the other.

The turns ratio of a transformer is defined as **the number of turns on its secondary divided by the number of turns on its primary**.

The standard accuracy classes of current transformer as per IS-2705 are **0.1, 0.2, 0.5, 1, 3 and 5 for metering CT**.

Application of CT Core According to Their Class.

Application | Accuracy Class | |
---|---|---|

Precession Metering | 0.1 or 0.2 | BL |

Commertial Metering | 0.5 or 1.0 | AM, BM, CM |

Ammeters | 1 or 3 | CD |

Protection Relays | 5P10 or 5P20 | STU |

Concept: Core Balance Current Transformer (CBCT) : It is **a ring-type current transformer through the center of which a three-core cable or three single-core cables of a three-phase system passes**. This type of current transformer is normally used for earth fault protection for low and medium-voltage systems.

Answer: Use the following formula for measuring ocean depth. **D = V Times 1/2** T D = Depth (in meters) T= Time (in seconds) V = 1507 m/s (speed of sound in water) Calculate the depth foe each of the times given below, using the formula above.

SCR power controllers compensate for mains voltage fluctuations **by employing RMS voltage regulation**. An SCR's voltage regulation mode adjusts the firing angle (phase angle) or duty cycle (zero cross) of the SCR output to maintain a constant voltage output proportional to the set point.

Physics Weightage For NEET 2022

Chapters | Questions Breakup |
---|---|

Optics | 4 |

Electrostatics and Electricity | 11 |

Heat & Thermodynamics | 4 |

Mechanics | 13 |

Dated : 21-May-2022

Category : Education