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Saturday, October 19, 2019
Three Phase Induction Motor Star-Delta Starter Complete Circuit Diagram(Power And Control Wiring)
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Monday, October 14, 2019
Saturday, October 12, 2019
How to find size of the electrical cable/wire for a given load?
How to find size of the electrical cable/wire for a given load?
1) Type of load : For feeder,control panel,distribution board (DB) or motor
2) Power Source : AC /DC power for Three phase or single phase
3) Full load current (Ampere)
4) Circuit Breaker size
5) Types of cable ( PVC,XLPE,Fire proof)
6) Installation Condition ( Underground, trunking,tray or conduit)
7) Distance / length of cable run from source to load
Calculation for sizing electrical cable/wire
Ib ≤ In ≤ Iz
Ib = Amperage load
In = Circuit Breaker size
Iz = Current rating for cable/wire
1) Type of load : For feeder,control panel,distribution board (DB) or motor
2) Power Source : AC /DC power for Three phase or single phase
3) Full load current (Ampere)
4) Circuit Breaker size
5) Types of cable ( PVC,XLPE,Fire proof)
6) Installation Condition ( Underground, trunking,tray or conduit)
7) Distance / length of cable run from source to load
Calculation for sizing electrical cable/wire
Ib ≤ In ≤ Iz
Ib = Amperage load
In = Circuit Breaker size
Iz = Current rating for cable/wire
Example :
We plan to install 1 unit induction motor 75 hp for running a water pump.Power factor value is 0.8 and motor efficiency is 0.85.Power supply for this motor is 415 volt 3 phase 50Hz.Distance from panel to motor is 75 meter.This panel and pump is located at outside of factory.Please size the suitable circuit breaker,electrical cable and also type of cable for this application.
Calculation
Ib ≤ In ≤ Iz
Ib = ( hp x 746) / (√3 x Volt x PF x Efficiency)
Ib = (75 x 746) / (√3 x 415 x 0.8 x 0.85)
Ib = 114.5 Ampere
In = Ib ≤ breaker sizing
In = 114 ≤ 150 ampere
In = 150 ampere (we decide to used MCCB 3 pole with 150 ampere rating)
Iz = In ≤ Iz
Iz = 150 ≤ Iz
Iz = 187 ampere ( carried capacity for 50mm² cable size)
So we decide to used cable size = 50 mm² with 4 core cable and clipped direct to cable tray.To confirm this cable size,we need to calculate the voltage drop.
Voltage Drop Calculation
Below is a voltage drop calculation that I made for cable power supply from panel to induction motor.
From Panel to Induction motor = 75 meter
mV = 0.87 (Refer Table)
Formula voltage drop : Vd = Ib x length(meter) x mV / 1000
Vd = (114.5 x 75 x 0.87) / 1000
Vd = 7.47 ( Acceptable refer to IEE 17th edition )
Ib = ( hp x 746) / (√3 x Volt x PF x Efficiency)
Ib = (75 x 746) / (√3 x 415 x 0.8 x 0.85)
Ib = 114.5 Ampere
In = Ib ≤ breaker sizing
In = 114 ≤ 150 ampere
In = 150 ampere (we decide to used MCCB 3 pole with 150 ampere rating)
Iz = In ≤ Iz
Iz = 150 ≤ Iz
Iz = 187 ampere ( carried capacity for 50mm² cable size)
So we decide to used cable size = 50 mm² with 4 core cable and clipped direct to cable tray.To confirm this cable size,we need to calculate the voltage drop.
Voltage Drop Calculation
Below is a voltage drop calculation that I made for cable power supply from panel to induction motor.
From Panel to Induction motor = 75 meter
mV = 0.87 (Refer Table)
Formula voltage drop : Vd = Ib x length(meter) x mV / 1000
Vd = (114.5 x 75 x 0.87) / 1000
Vd = 7.47 ( Acceptable refer to IEE 17th edition )
* Voltage drop acceptable value is 4% x 415 volt = 16.6 Volt
Conclusion
Conclusion
From this calculation, we are fully confident to laying cable size 50mm² with 150 ampere of MCCB, using multi-core PVC Armored cable (due to outdoor wiring application) and also cable laying with cable tray.
That is why all Electrician and Electrical Engineer need to know about cable sizing calculation to make sure wiring installation project successful and meet the requirement of Electrical Safety and Regulation without any disaster.
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That is why all Electrician and Electrical Engineer need to know about cable sizing calculation to make sure wiring installation project successful and meet the requirement of Electrical Safety and Regulation without any disaster.
For Complete Cable Chart In PDF Format Send Us Your Email Address. Comment your email address on one of our YouTube video, chart will be forwarded to your given email address. Remember comment only on YouTube Video.
Subscribe to our YouTube channel for simple chart.
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