What is Voltage Drop

S

VD = IR = (mV/A/m)r

p.f. = 1LoadI R

Source

What is Voltage Drop

S

S

VD = IR = (mV/A/m)r

VD = IR Cos == Cos(mV/A/m)r

Load

p.f. = 1Load

p.f. = Cos

I

I

R

R

Source

Source

What is Voltage Drop

S

Source

Load p.f. = Cos

VD = IR Cos + I X Sin ==Cos(mV/A/m)r + Sin(mV/A/m)x

S

S

VD = IR = (mV/A/m)r

VD = IR Cos == Cos(mV/A/m)r

Load

p.f. = 1Load

p.f. = Cos

I R

I

I

R

R

Source

Source

X

Why Need to Control Voltage Drop

1. Meet the relevant Code (CP5: 525-01-02)

2. Maintain Proper Operation (CP5: 525-01-01)

3. Operate Best Efficiency

4. Safety Operation

5. Optimize Life Span

6. Reduce Energy Loss

7. Reduce Heat

Ways to Minimize Voltage Drop

1. Reduce Route Length

2. Bigger Cable

3. Lower Conductor Resistivity

4. Lower Cable Reactance

5. Boost up Supply Voltage

6. Use Higher Supply Voltage

7. Parallel Circuit

8. Reduce Temperature of Operation

9. Review Installation Method

DISTRIBUTION ARRANGEMENT

RADIAL RISER SUB-DISTRIBUTION

RING

Min. V.D. 0.23 % 0.18 % 0.13 % 0.11 %

Max. V.D. 0.92 % 0.47 % 0.39 % 0.28 %

Installation Cost 100 % 180 %) 170 % 210 %

Voltage Drop Vs Distribution ArrangementEach Load = 100A

Distance of Each Load = 3m

N N NN

Voltage Drop Vs Different Type of Distribution Means

Load = 100A

Distance = 100m

Voltage Drop Limit

CP5 525.01

V.D. 4%

Supply Utility Voltage Regulation = 6%

Most Electrical Appliance Operate properly within Voltage Regulation = 10%

V.D. Limit = 4%

10%

6%

4%

6%

Typical Allowable Voltage Drop

3.0%

1.5% 1%

3.0% 4%

2.5% 3%

1.0%

V.D.

10%

6%

Final Circuit Voltage Drop

Sub-Main Voltage Drop

Supply Utilities Voltage Regulation

Lift/Escalator Lighting Small Power

6% 6% 6% 6% 6%

ACMV MCC

Fire Pump UPS Load

1.0%

Voltage Drop at Steady State / Transient Condition

S B

MLoad3% 3%

1%

S B

M 3%

Load

1%

NN

3%

2%2%

Voltage Drop at Steady State / Transient Condition

S B

MLoad5%

3% 3%

6%

2%

1%

S B

M 3%

6%Load

1%

2%

NN

3%

4%

3%

2%

4%

2%

Voltage Drop with Consideration of Cable Reactance

2.5%

2.5% 2.5%2.2%

1.3%

0.9%

1.6%

6mm2 16mm2 25mm2 240mm2 500mm2

1.2%

0.3%

(Voltage Drop)r = IR (Less Than 16sq mm)

(Voltage Drop) R , X, Cos = IRCos + I X Sin

Voltage Drop with Temperature Correction Cable (R & X) data given @ Rated Cable Temp.

(e.g. 70oC Conductor Temp. for PVC Cable-30oC Ambient)

I Temp R V.D.

Load

Ambient Temp = 25oC

I(design)=20A

1/c 10sqmm PVC cable

I(table) =59A

(mV/A/m)r=3.8mV/A/m

30m

VD=3.8mV*20A*30m=2.28V

Voltage Drop with Temperature Correction Cable (R & X) data given @ Rated Cable Temp.

(e.g. 70oC Conductor Temp. for PVC Cable-30oC Ambient)

I Temp R V.D.

Load

Ambient Temp = 25oC

I(design)=20A

1/c 10sqmm PVC cable

I(table) =59A

(mV/A/m)r=3.8mV/A/m

VD=3.8mV*20A*30m=2.28V

30m

Voltage Drop with Temperature Correction