DESAIN KOMPRESSOR (Dasar Electrical)

CONTENT: 

• Beberapa definisi dan hukum dasar: DC, AC satu phase, AC tiga phase
• Sistem 3 phase :  koneksi "START" dan "DELTA"
• Data motor
•  Motor Insulation Class and service factor
•  Motor protections : - Electrical protections and- Overload protections
•  How to read a service diagram
•  Device connections and measurements

LECTRICITY  :   What ? 

 Something   - INVISIBLE

- POWERFULL

- DANGEROUS !!

 Something  - SIMPLE  for QUALIFIED PEOPLE

POWER SOURCES   :

Direct Current (DC)

Voltage is polarised with + and -

•  Examples : Batteries

Rectified power supplies ; 12….24 V

•  Applications :  Electronic instrument supplies

Control equipment

Supply for pressure transmitter, etc...

•  Safety : Voltages up to 24 VDC are safe, higher voltages can be

   dangerous for people.

Alternating Current (AC) - Single Phase

Characteristic : Voltage and current regularly changes strength and direction in a sinusoidal variation

Application : General use

Alternating Current (AC) - Single Phase

Characteristic parameters : Period T = Time for 1 cycle

                                       Frequency (Hz) = 1/T

                                       50 HZ = 50 periods per second

                                       60 Hz = 60 periods per second

                                       RMS value :  = max amplitude divided by sqrt 2 (For sinus)

Safety : - A.C. Voltage  <= 24 V is Safe for personnel

       >  24 V is dangerous

Terminology : < 50 V     : extra low voltage

  < 1000 V  : Low voltage

      1000 V < U < 10000 V : Medium voltage

                > 10000 V : High voltage

Alternating Current (AC) - Three Phase

Characteristics :

•  Three phase alternating current is produced in a generator with three separate windings.All values on the sinusoidal voltage are displaced 120° in relation to each other.

Power factor :

Relation between Reactance (X) - Resistance (R) -

Impedance (Z) - Phase displacement (j)

Basic laws :

       (Direct Current) DC

Law of Ohm:

I =   U / R  ,,,,,,, with I  =  Current in Ampere

         U = Voltage in Volt

         R = Resistance in Ohm

 Absorbed power:

P = U x I  ....... with U = Voltage in Volt

         I = Current in Ampere

         P = Power in Watt

         (Alternating Current)  AC

 Law of Ohm:

   I =  U / Z........   with  I =  Current in Ampere

                                   U = Voltage in Volt

                                   Z = Impedance in Ohm

           = Sqrt (R² + X²) where X is the reactance

 Power in a single phase system:

P = U x I x cos j

 Power in a three phase system:

P = UL x IL x cosj x Sqrt (3)    with:

 P = Power in Watt ( other units as stated above)