Harmonic Allowable limit as per CEA Guidelines

As per the CEA Guidelines, those who  maintaining the Substation in the voltage level of 11KV,22KV,33KV, they should maintain the total Harmonic distortion as per the below allowable limit.

Individual Voltage Harmonic Distortion :

Maximum acceptable limit is 3% 

Total Voltage Harmonic Distortion :

Maximum acceptable limit is 5% 

Total Current Harmonic Distortion :

Maximum acceptable limit is 8% 

This limit has mentioned by institute of electrical and electronic engineer (IEEE 519 2014)

If THD is breaching the acceptable limit, then you have to install harmonic filter to maintain the level as stated by above standards, otherwise government authority will impose the penalty.

The Harmonic filter may be active harmonic filter or passive harmoic filter or hybrid harmoic filter.However, the selection of filter is based on your site load requirement. 

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Ashokraj  S

How to calculate efficiency of air cooled chiller ?

Chiller efficiency is generally expressed interms  of iKW/TR. 

Where,

i stands for indicated 

KW stands for kilo watt 

TR stands for ton of refrigeration 

iKW/TR is nothing but the ratio of electrical power input to the compressors to ton of cooling produced by the equipment.

Less value of iKW/TR indicates high efficiency of chiller

Higher value of iKW/TR indicates low efficiency of chiller.

The chiller performance test is usually carried out once in year by the chiller OEM

During the performance test, OEM will bring power quality analyser and ultrasonic clamp on flow meter to the site .

Ultrasonic clamp on flow meter will be installed at return chilled water pipeline of chiller.This flow meter will sense the flow rate of fuild flowing through the chiller. The flow rate can be expressed in gpm or m3/hr.

The power quality analyser will be installed at input power supply consumed by chiller/compressor. 

To calculate the TR of chiller, we have to use the below formula 

TR =(gpm x delta T)/24

Where 

Gpm is gallon per minute 

Delta T is temperature difference between entering and leaving chilled water temperature 

Once you find out the TR of chiller by using the above formula,then you can find out iKW/TR. 

For example:

Kw of chiller at 100% load is 2

Ton of refrigeration of chiller is 2

Formula to find out chiller efficiency is 

iKW/TR =2/2=1 

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Ashokraj S