Synchronous Generator or Alternator
Subject and UNIT: Electrical Machines II: UNIT I: c. Synchronization and Parallel Operation of Alternators Engineering Electrical Machines - II
The heating is caused by losses so ultimately rating of machine depends on losses.
Synchronous Generator or Alternators
Subject and UNIT: Electrical Machines II: UNIT I: c. Synchronization and Parallel Operation of Alternators Engineering Electrical Machines - II
The short circuit transients in a synchronous machine is a complicated phenomenon due to number of circuits coupled to each other are involve
Subject and UNIT: Electrical Machines II: UNIT I: c. Synchronization and Parallel Operation of Alternators Engineering Electrical Machines - II
The stray load losses and direct load losses together called short circuit load losses.
Subject and UNIT: Electrical Machines II: UNIT I: c. Synchronization and Parallel Operation of Alternators Engineering Electrical Machines - II
When two alternators are connected in parallel we have seen that a change in the excitation changes the terminal voltage and p.f. is determined by load.
Alternator
Subject and UNIT: Electrical Machines II: UNIT I: c. Synchronization and Parallel Operation of Alternators Engineering Electrical Machines - II
For any alternator its driving torque can be changed by controlling the gate opening in case of hydrogenerators or by controlling the throttle opening in case of turbogenerators.
Subject and UNIT: Electrical Machines II: UNIT I: c. Synchronization and Parallel Operation of Alternators Engineering Electrical Machines - II
Consider again two alternators running in parallel with each alternator supplying one half of active power and one half of reactive power.
Alternator on No Load
Subject and UNIT: Electrical Machines II: UNIT I: c. Synchronization and Parallel Operation of Alternators Engineering Electrical Machines - II
Let us consider the effect of change in excitation on alternator with and without load.
Subject and UNIT: Electrical Machines II: UNIT I: c. Synchronization and Parallel Operation of Alternators Engineering Electrical Machines - II
It has already been seen that in case of interconnected systems at power stations number of alternators are operating in parallel.
Subject and UNIT: Electrical Machines II: UNIT I: c. Synchronization and Parallel Operation of Alternators Engineering Electrical Machines - II
The expression for salient pole machines can be derived as follows
Alternators
Subject and UNIT: Electrical Machines II: UNIT I: c. Synchronization and Parallel Operation of Alternators Engineering Electrical Machines - II
The method used to determine Xd and Xq, the direct and quadrature axis reactances is called slip test.
Subject and UNIT: Electrical Machines II: UNIT I: c. Synchronization and Parallel Operation of Alternators Engineering Electrical Machines - II
According to this theory the armature m.m.f. can be divided into two components as, 1. Component acting along the pole axis called direct axis. 2. Component acting at right angles to the pole axis called quadrature axis.
Alternators
Subject and UNIT: Electrical Machines II: UNIT I: c. Synchronization and Parallel Operation of Alternators Engineering Electrical Machines - II
In the local circuit the two voltages E and V are in phase opposition while in the external circuit they are in the same phase.