পার্থক্য লিখ- (a) ইম্পালস ও রিয়‍্যাকশন টারবাইনের মধ্যে (b) ওয়াটার টিউব ও ফায়ার টিউব বয়লারের মধ্যে। (Write down one difference between (a) impulse and reaction turbine (b) Water tube and fire tube boiler.)

Conditions for parallel operation of 3-phase transformers (in points):

• Voltage rating should be same.
• Turns ratio should be same.
• Vector group and phase sequence should be same.
• Impedance (p.u.) should be same.
• Polarity should be same.
• Load sharing capacity should be proportional as per rating.

1-2 Isentropic compression in a pump

2-3 Constant pressure heat addition in a boiler

3-4 Isentropic expansion in a turbine

4-1 Constant pressure heat rejection in a condenser

• Proportional Limit
• Elastic Limit
• Upper Yield
• Lower Yield
• Ultimate Stress
• Breaking Point

Open Circuit Test of Transformer : The main objective of this test is to find out the core loss (iron loss) and no-load parameters of the transformer. Procedure: In this test, the high-voltage (HV) winding of the transformer is kept open, and the rated voltage is applied to the low-voltage (LV) winding.

Result : Since no load is connected, the transformer draws very little current. As a result, the copper loss (I2R) is almost negligible. In this situation, the reading of the wattmeter directly indicates the core loss. These losses are mainly due to hysteresis and eddy current.

Open Circuit Test on Transformer

Short Circuit Test of Transformer: The main objective of this test is to find the full-load copper loss of the transformer and its equivalent series parameters, such as Resistance, Reactance, and Impedance.

Procedure : In this test, the low-voltage (LV) winding is shorted, and a very small voltage (about 5-10% of the rated voltage) is applied to the high-voltage (HV) winding. This voltage is gradually increased until the rated current flows.

Result : Since the voltage is applied very low, the flux in the core is also very low, so the core loss is considered negligible. Therefore, in this situation, the reading of the wattmeter directly indicates the full-load copper loss. Using the results of these two tests, it is possible to determine the efficiency and voltage regulation of a transformer at any load and power factor.

Short Circuit Test on Transformer

(i) WIMAX = Worldwide Interoperability for Microwave Access.

(ii) WiFi Wireless Fidelity.

(iii) HTTP = Hyper Text transfer protocol.

(iv) LASER = Light Amplification by Stimulated Emission of Radiation.

(v) HTML = Hyper Text Markup Language.

(vi) RFID = Radio Frequency Identification