The document discusses the capacitance of power cables and its effects on electrical power systems. The capacitance depends on cable length and can increase dielectric losses, affecting actual power. Reactors are used to compensate for capacitance and minimize losses. While cable capacitance provides reactive power, it is uncontrolled and distributed, so external capacitors are still needed for power factor improvement. Capacitance can increase voltage above safe limits and damage insulation if not controlled. Cable capacitance acts as a shunt compensation in parallel with loads rather than a series compensation. The capacitance is modeled as a lumped capacitor connected in parallel to the load and series resistance and inductance, though in reality it is distributed along the cable length.

1. EPDU ASSIGNMENT
CAPACITANCE OF THE CABLES
Name:Rahim Pervez Noorani Roll #: TE-EE-078
1. Will the capacitance of power cables have an effect on the active power of the system?
Yes, the capacitance of cables depends upon the length of cables, higher the length higher will be the
capacitance and it wouldrequire more charging current, hence it would increase the dielectric losses in the cable
and would affect the actual power of the system. Therefore we use reactors to compensate the capacitance and
minimize dielectric losses.
2. If we provide capacitance through power cables will there be requirement of external capacitors for Power
Factor improvement?
The capacitance of the cable is distributed (not lumped) and uncontrolled therefore the cable capacitance will
not help in Power Factor Improvement (PFI); we have to use shunt capacitive banks in parallel with load for PFI.
3. What are the pros and cons of the capacitance of power cables?
The capacitance of the cable supplies reactive power which enhances the capacity of system to address more
loads.
The cable capacitance produces dielectric losses which decreases the efficiency of the system.
The uncontrolled capacitance would supply uncontrolled reactive power which would increase the voltage in the
cable above limits which damage the insulation of the cable.
4. Is capacitance of power cable is a series compensation or a shunt compensation?
The capacitance of the cable in shunt compensation, it is connected in parallel with load to regulate the voltage
magnitude, while series compensation is the connection of component in series with the load to control the
impedance of line and other losses in the system.
5. Describe the model of capacitance in power cables.
The model of power cable consists of a resistance R and inductor L connected in
series with the load and a capacitor C connected parallel with the load.
Capacitance is directly proportional to length of cable.
In this model the capacitance of cable is assumed to be lumped but actually the
capacitance of cable is distributed.