4. Prepared by: Dr. Ahmad Al-Subhi
- Basically, there are two signals in the line:
1. Power signal (in Hz).
2. Communication signal (in kHz-MHz range).
- Carrier wave communication uses up to 150 kHz to 800 kHz
frequency to send all the communication.
- These high frequencies can damage the power system
components which are designed to operate at 50 or 60 Hz.
- Wave trap (called also a line trap) is a LPF (low pass filter)
which allows the 60 Hz power signal to pass through it and
blocks the high-frequency carrier signal from entering the power
substation.
6. - Wave trap is connected in series with the transmission line.
- However, this causes resonance with capacitors like line
capacitors, capacitive voltage transformer capacitor …etc.
- Inductive reactance: XL = 2πf L
Prepared by: Dr. Ahmad Al-Subhi
7. - To solve this, inductance is shunted by a tuning capacitor in
order to tune the line trap to the desired blocking frequency.
- It provides a high impedance to carrier frequencies and low
impedance path for the power frequency.
Prepared by: Dr. Ahmad Al-Subhi
8. - Currently, PLCs are replaced by OPGW (Optical Ground Wire).
- OPGW acts as normal ground wire protecting phase wires from
lightning strikes and carries earth fault current.
- Apart from its application as an
earth wire, OPGW also provides
an optical path in power line
installations for communication
& protection needs.
- OPGW eliminates the coupling capacitor & wave trap thereby
reducing the system complexity and enhancing the reliability.
Lecture 9d: ATS and UPS
Prepared by: Dr. Ahmad Al-Subhi
