electrical-engineering

## What I do - Design electrical circuits and systems - Analyze power systems and distribution - Design digital and analog electronics - Specify electrical equipment and components - Ensure compliance with electrical codes ## When to use me - When designing electrical systems for buildings or facilities - When analyzing power distribution - When selecting electrical equipment - When designing electronic circuits - When working on power generation or transmission ## Key Concepts ### Circuit Analysis ```python import numpy as np from scipy import signal # Ohm's Law def ohms_law(V=None, I=None, R=None): """Calculate unknown using V=IR""" if V is not None and R is not None: return V / R elif V is not None and I is not None: return V / I elif I is not None and R is not None: return I * R # Kirchhoff's Current Law (KCL) def kcl(node_currents): """Sum of currents at node = 0""" return sum(node_currents) # Kirchhoff's Voltage Law (KVL) def kvl(loop_voltages): """Sum of voltages in loop = 0""" return sum(loop_voltages) # Power calculations def electrical_power(V, I=None, R=None): """P = VI = I²R = V²/R""" if I is not None: return V * I elif R is not None: return V**2 / R # AC circuits def impedance(R, X_L=0, X_C=0): """Complex impedance Z = R + j(XL - XC)""" return complex(R, X_L - X_C) def apparent_power(P, Q): """S = √(P² + Q²)""" return np.sqrt(P**2 + Q**2) def power_factor(P, S): """PF = P/S""" return P / S ``` ### Circuit Theorems ```python # Thevenin equivalent class TheveninEquivalent: def __init__(self, V_th, R_th): self.V_th = V_th # Open circuit voltage self.R_th = R_th # Equivalent resistance def max_power_transfer(self): """Maximum power when R_load = R_th""" return { "R_load": self.R_th, "P_max": self.V_th**2 / (4 * self.R_th) } # Norton equivalent class NortonEquivalent: def __init__(self, I_n, R_n): self.I_n = I_n # Short circuit current self.R_n = R_n # Equivalent resistance ``` ### Power Systems ```python # Three-phase power class ThreePhasePower: @staticmethod def line_to_phase(V_line, connection="Y"): if connection == "Y": return V_line / np.sqrt(3) else: # Delta return V_line @staticmethod def total_power(V_line, I_line, PF): # Y: S = √3 × V_L × I_L # Δ: S = √3 × V_L × I_L S = np.sqrt(3) * V_line * I_line P = S * PF Q = S * np.sqrt(1 - PF**2) return {"S": S, "P": P, "Q": Q} @staticmethod def voltage_drop(percent, V): """Allowable voltage drop""" return percent / 100 * V ``` ### Electronic Components | Component | Symbol | Function | |-----------|--------|----------| | Resistor | R | Current limiting, voltage division | | Capacitor | C | Energy storage, filtering | | Inductor | L | Energy storage, filtering | | Diode | D | One-way current flow | | Transistor | Q | Amplification, switching | | Op-Amp | UA | Signal amplification | ### Filter Design ```python # First order low-pass filter def lp_filter_fc(R, C): """Cutoff frequency f_c = 1/(2πRC)""" return 1 / (2 * np.pi * R * C) # Sallen-Key second order def sallen_key_components(fc, Q): """Calculate component values""" # Given fc and Q, solve for R and C wc = 2 * np.pi * fc # R1 = R2 = R, C1 = C2 = C C = 1 / (wc * Q * R) # Solve for C given R return {"R": R, "C": C} ``` ### Electrical Codes - **NEC (NFPA 70)**: National Electrical Code - **IEC**: International Electrotechnical Commission - **IEEE**: Institute of Electrical and Electronics Engineers - **UL**: Underwriters Laboratories safety standards - **NEMA**: National Electrical Manufacturers Association