Induction motors are the main load as industrial drives in industrial load areas, hence with the reduction in frequency would reduced the loading too, as Ns=120f/P, …..

The energy meter you mentioned, Inhe Meter, is a type of digital energy meter that measures various parameters of electricity consumption, including voltage, current, power, and frequency. In Bangladesh, the frequency of the power system is supposed to be maintained within a range of 50 Hz ± 0.5 Hz.

However, it is not uncommon for the frequency of the power system to fluctuate due to various factors, such as changes in power demand, generator output, or faults in the system. These fluctuations may cause the frequency to deviate outside the acceptable range of 50 Hz ± 0.5 Hz, as you mentioned.

In such cases, it is possible for the energy meter to detect the frequency deviation and display it to the user, but it may not necessarily trip the overall system. This is because the power system is designed to withstand a certain level of frequency deviation without tripping or causing damage to the system.

The ability of the power system to withstand frequency deviations is known as its frequency response capability. This capability is achieved through various measures, such as the use of frequency-dependent relays, load shedding, and generator control systems, among others.

In Bangladesh, the power system operators are responsible for monitoring the frequency of the system and taking appropriate measures to maintain it within the acceptable range. This may include adjusting generator output or shedding load in response to frequency deviations.

Overall, while frequency deviations outside the acceptable range may be detected by the energy meter, they may not necessarily result in the overall system tripping if the system has sufficient frequency response capability to withstand the deviation.

The permissible variation of frequency in power systems can vary depending on the specific grid codes, regulations, and standards set by the relevant authorities in a given country or region. These values can differ from one country to another.

For Bangladesh, according to the Bangladesh Energy Regulatory Commission (BERC) Grid Code, the permissible variation of frequency in the power system is as follows:

These values indicate that the acceptable frequency variation under normal operating conditions is ±1% (50 Hz ± 0.5 Hz) and ±2% (50 Hz ± 1.0 Hz) under contingency or emergency situations.

It is essential for the power system operators to maintain the frequency within the permissible range to ensure the stability, reliability, and proper functioning of the grid and connected equipment. Failure to maintain the frequency within the specified range can lead to undesirable consequences such as equipment damage, tripping of protection devices, and even large-scale blackouts.

Permissible deviations of frequency in Azerbaijan is stricter. E.g. for the long-term regime it is ± 0.2 Hz, for short-term (emergency) modes ± 0.4 Hz at standard frequency 50 Hz.