Essential Q&A on Electrical Earthing and Protection Systems
Fundamental Questions on Electrical Protection and Distribution
1. What device eliminates fault currents in a TT system?
Fault currents in a TT system are preferably eliminated by a Residual Current Device (RCD).
2. Which earthing system arrangement is used in public distribution facilities?
In public distribution facilities, the earthing system commonly used is the TT system.
4. Which are the three basic types of earthing (neutral) systems?
The three basic types of earthing systems are:
- TT
- TN (TN-C, TN-
PN Junction vs. Zener Diode: Semiconductor Device Comparison
Here’s a clear and structured comparison and explanation of PN junction diode and Zener diode, two fundamental semiconductor devices:
🔹 PN Junction Diode
✅ Definition:
A PN junction diode is a semiconductor device formed by joining P-type and N-type materials. It allows current to flow only in one direction — from the anode (P-side) to the cathode (N-side).
⚙️ Working Principle:
Forward Bias: When the P-side is connected to the positive terminal of a battery and the N-side to the negative
Computer Architecture: Key Formulas and ISA Comparison
Key Computer Architecture Formulas
Mean Time Between Failures (MTBF) = MTTF + MTTR. Availability (Reliability) = MTTF / MTBF. Failure Rate = 1/ MTTF. Speedup of X relative to Y = Execution timeY / Execution timeX. Speedup = Execution time for entire task without using enhancement / Execution time for entire task using enhancement when possible. Speedup_overall = Executiontime_old / Executiontime_new = 1 / (1 – Fraction_enhanced) + (Fraction_enhanced / Speedup_enhanced). CPU time = CPU clock cycles
Read MoreProcessor Performance Analysis: Frame Buffer, Clock Rates, and Compilers
Frame Buffer and Network Transmission
Consider a color display using 8 bits for each of the primary colors (R, G, B) per pixel and a frame size of 1280×1024.
- Minimum Frame Buffer Size: The frame size is 1280 * 1024 = 1,310,720 pixels. With 3 bytes per pixel (one for each color), the minimum frame buffer size is 1,310,720 * 3 = 3,932,160 bytes.
- Transmission Time: The transmission time over a 100 Mbit/s network is (3,932,160 * 8 bits) / (100 * 106 bits/second) = 0.3145728 seconds, or 315 ms.