HVAC (Heating, Ventilating, and Air Conditioning)

Heating, Ventilating, and Air Conditioning

The three central functions of heating, ventilating, and air-conditioning are interrelated, providing thermal comfort, acceptable indoor air quality, within reasonable installation. operation, and maintenance costs. HVAC system can provide ventilation, reduce air infiltration, and maintain pressure relationships between spaces. How air is delivered to, and removed from spaces is known as room air distribution.

from my power plant project

maintain temperature and humidity and prevent out side dirt air by pressure maintain.

Those are purpose of HVAC system installed at the electrical(RTU, battery) room

Air conditioning, fresh air fan installed At the electrical room, RTU room.

Air conditioning, fresh air fan, Exhaust fan(Ventilating) installed At the battery room.

--> Hydrogen generate from the battery in case of accident, that's why Exhaust fan required and the Gas detector also required for this function.

FFU(Fan filter unit) installed at the enclosured building like turbine building.

--> Differential pressure meter installed at the FFU for the filter unit cleaning.

Do you wanna know about air compressor and dryer ?

We are using this type of air compressor.

Screw type air compressor


Rotary screw air compressor operation principle Youtube

A rotary screw compressors use two helical screws, known as rotors, to compress the gas. In a dry running rotary screw compressor, timing gears ensure that the male and female rotors maintain precise alignment. In an oil-flooded rotary screw compressor, lubricating oil bridges the space between the rotors, both providing a hydraulic seal and transferring mechanical energy between the driving and driven rotor. Gas enters at the suction side and moves through the threads as the screws rotate. Clearances between the threads decrease and compress the gas. The gas exits at the end of the screws. (from wikipedia)

From the view of control circuit, air compressor using star-delta starter for the main motor (for compressor) and It operates with its pre-determined pressure (we are using 7.4bar for plant main air compressor, and the other for ash handling system setted at 6.5 or 7 bar). for the industrial applications, air compressor need load/unload function for its continuous air consumption over the whole plant instrument and other consumptions.


Air dryer
There are several types of air dryer, and we are using Heatless type and refrigerated type

Heatless Type Air / Gas Dryers.
The working principle of heatless air dryer is based on “Pressure swing absorption” and the operation is fully automatic & simple. The moisture from compressed air/gas is removed by absorption. Two drying towers are provided that keep on changing their position according to the designed cycle. While in one chamber drying of air is in operation, the other gets re-generated by de-pressurization and using a small portion of the dried air. This dried air flushes out the moisture from the absorption media, absorbed in previous cycle. Slide piston valve, pneumatic diaphragm operated exhaust valves are provided for complete automatic change over. Moisture level 80 ppm(dew point - 40 degree C) or less can be achieved. The dryer is very compact and very easy for operation and maintenance.

Heat regenerated type dryer
In these air dryers, external heat used for regeneration of the absorbent. and various dryers that are classified as under
- Internal heaters type : The electric heaters are embedded in the drying towers which heat up absorption media upto required degree and the absorbed moisture is then flushed out with the help of a very small amount of dried air / gas.
- Blower heat regenerated ; In blower heat regenerated dryer, we can save compressed air which is to be washed in regeneration. A blower provides the atmospheric air which is heated in an external heater and is passed throuth the drying tower from where it takes away all the moisture.
- No purge loss split flow type : The wet compressed air/gas is split at the inlet through differential valve. Part of the stream is passed through an external heater and then the tower regeneration where it carries the absorbed moisture and then passed through a cooler where the absorbed moisture is condensed and separator.
- Heat of compression type : In heat of compression dryer, hot compressed air from compressor is directly passed through the drying tower to be regenerated and hence the use of heater is eliminated. However, a small capacity electric heater is provided in the incoming hot air line which takes care of the lower temperature of the hot air due to any reason. There is considerable power saving in this type of dryer and dew point upto -50 degree C. can be achieved.
--> we are not using this type of dryer

Refrigerated type Air Dryer
Refrigerated air dryer is the most commonly used compressed air dryer for most industrial applications. It is extensively used for the drying of plant air and other utility gases like hydrogen gas, nitrogen drying etc. In this type of dryers the moisture present in the compressed air / gas is condensed by chilling it down from 0 degree C to 4 degree C(?) by using effective refrigeration cycle and the condensed moistures is separated by efficients filters. The dew point is 23 degree C (at atmospheric pressure) but the running cost is very low. A full range of air-cooled as well as water cooled refrigerant air dryers are available for moisture removal & to provide dry clean air to any size and type of compressed air & pneumatic systems.

you can see the gray panel rear side of the air compressor, this is refrigerated air dryer.

Disassemble-MCCB(moulded case circuit breaker)

Circuit breakers are electrical component to isolate the electricity.
There are several types of circuit breakers but, as i know ( you have to remember i am a just beginer with 5 year experience)
- Circuit breaker for Power distribution
- Circuit breaker for Motor protection


after remove front cover
vacancies near the switch are for the auxiliary switch for breaker on-off status and breaker trip
This is normal accessary for the breaker. (but not in the photo)


This is electronic card for fault detection such as
For Power distribution
- Protection against overload ( L : ABB breaker says )
- Protection against short-circuit with time delay ( S : ABB breaker says)
- Instantaneous protection against short-circuit ( I : ABB breaker says)
- Protection against earth fault ( G : ABB breaker says)
For Motor Protection
- Against overload with inverse time delay trip and trip characteristic according to an inverse time curve ( L : ABB breaker says)
- Against rotor block with delayed trip and trip characteristic with definite time ( R : ABB breaker says)
- Against short-circuit with Instantaneous trip ( I : ABB breaker says)
- Against phase current unbalance or loss of phase with delayed trip and trip characteristic with definite time ( U : ABB breaker says)
... There will be more than i know


you can see the black component which can measure the current to utilize the protection function.


you can see the component which is connected with 2 wire. this is trip shunt to activate the breaker trip this will actuated by the card signal.




main contactor part consist of moving part for on, off and stationary part for connect the power cable (or bus bar)
at the picture the black color mean there was a big breaking current



What ever the maker is, the basic operation of breaker is same but the structure and accessary compartment is different.

Disassemble-Power contactor[Magnetic contactor]

Power contactor part


actuator type (electromagnetic)


actuator type (electromagnetic)

I tried to disassemble Power contactor and it was easy to disasseble , we can change the electromagnetic actuator part with different voltage (AC, DC).
The Power contactor part have a lifetime during its continuous operation.
If the application needs lots of operations then need to find other equipment for good practice.

Commissioning organization

1. Commissioning Manager
2. Coordinator and document controller
3. Administration Manager (can be organized with Construction)
3. HSE Manager (can organized with Construction)
4. Commissioning Boiler Manager
5. Commissioning BOP Manager
6. Commissioning Turbine Manager
7. Commissioning E&I Manager
8. Quality Manager (or can be organized under the each part Manager)
9. Engineers and Technitians


This organization will be different based on the company.

Power system connection overview

Preface of my work

- Electrical, Instrument & Control (Instrument and control part weak part, still need more experience and study)

Power receiving (Power feeding, power energization)
- Check the contstruction statue and quality. (Construction complete certificate)
- Check required document for the power receiving (approved drawing, quality document, protection relay calculation sheet, equipment site test item & procedure & test protocol, contractual requirements)
- Check function & interlocking test of equipment

Related equipment
- GIS (230kV, 115kV High voltage, . . . )
- Generator step up transformer (230kV, 115kV . . . )
- Unit Aux Transformer for house load consumption
- Exciation Transformer for Generator excitation system
- Generator circuit breaker
- Generator
- MV Switchgear
- LV Switchgear
- Motor control center
- Local panel for various equipment
- Protection panel (GIS, Transformer, Generator, Transmission line)
- Control system ( DCS, SCADA, PLC )


Operation & control
- Operation of above equipment
- All kind of electrical equipment (Motors, VFD, Heaters, Motor operating valve, solenoid)