# What is constant in synchronous generator?

## What is constant in synchronous generator?

Synchronous generators can operate in P-V (constant active power and terminal voltage) or P-Q (constant active and reactive power) modes while in a grid-connected operation.

What is armature time constant?

The armature short circuit time constants refers to the time for the dc current component in the armature to decay following the application of a short circuit. The values are in tenths of a second, and are provided for a three-phase, phase-to-phase, and phase-to-neutral fault.

How do you calculate synchronous reactance of a generator?

Saturated Synchronous Reactance Hence, the value of the synchronous reactance to be used in a given problem should be one calculated at the approximate load on the alternator. If the alternator is connected to the infinite bus, then its terminal voltage remains the same at the bus value. 𝑍𝑠(sat.) =𝐸𝑎𝑐𝐼𝑎𝑏=𝑅𝑎+𝑗𝑋𝑠(sat.)

### Why the speed of the synchronous generator should be kept constant at synchronous speed?

Speed of synchronous generator should be constant at no or any load as speed is directly related to the frequency of voltage generated by generator and changing frequency can not be to tolerated in the electric supply system.

Is synchronous generator the is not constant?

In electrical machinery and power systems, the synchronous reactance is treated as a constant reactance in series with the generated emf and is independent of load condition.

What is Subtransient period?

First, “subtransient” refers to the fact that this quantity operates extremely fast—faster than even “transient.” In technical terms, the subtransient time period lasts from about one to three cycles, which is from 16.7 milliseconds to 50 milliseconds (assuming a power frequency of 60 Hz).

#### What is stator time constant?

It shows that a long-time inverse-time overcurrent relay applied with minimal coordination margin can provide conservative overcurrent protection for motor overload. where: t is the time to reach the limiting temperature. TC is the stator thermal time constant. I is the current in per unit of rated full load.

What is field time constant?

The time constant of the field current to decay to its pre–fault value is also Td” (if a constant field voltage, as we have applied in this case). This can be verified from the field current plot in Figure 5. Thus, after a time period equal to Td’, the field current will decay to around 37% of its initial value.

How do you calculate synchronous impedance?

Zs = E/Sic. At higher values of field current, saturation increases and the synchronous impedance decreases. The value of Zs calculated for the unsaturated region. The O.C.C is called the unsaturated value of the synchronous impedance.

## What is the synchronous impedance?

The synchronous impedance (ZS) is an imaginary impedance employed to account for the voltage effects in the armature circuit of the alternator, which is produced by the actual armature resistance, the actual armature leakage reactance, and the effect of the armature reaction. Manish Kumar Saini.

How to calculate synchronous impedance and voltage regulation for a generator?

For a synchronous generator following are the equation given below: For calculating the synchronous impedance, Z s is measured, and then the value of E a is calculated. From the values of E a and V, the voltage regulation is calculated. The measurement of synchronous impedance is done by the following methods. They are known as:

Why synchronous impedance is constant?

The synchronous Impedance is constant The synchronous impedance is determined from the O.C.C and S.C.C. It is the ratio of the open-circuit voltage to the short circuit current. When the O.C.C and S.C.C are linear, the synchronous impedance Z S is constant.

### What is the synchronous speed of a generator?

Its rotation speed is known as synchronous speed because its rotation speed equals the speed of rotation of field at stator that known as synchronous speed. Due to this, it used in such an application where constant speed is essential. It mostly used in our generation structure for the creation of energy.

What are the generator’s time constants?

The generator’s time constants refer to the subtransient and transient time periods, specified in seconds, immediately following either a short circuit or open circuit applied to the armature terminals.