MAST A 0543709 - Caterpillar

Ohm's Law
E = IRwhere E = voltage in voltsI = current in amperesR = resistance in ohmsBy simple algebra this equation may be written:Power
P = IEwhere P = power in wattsI = current in amperesE = voltage in voltsThis equation for power may also be transposed to:From Ohm's law it is known that E = IR. If this expression for voltage is substituted in the power law, we can derive the additional equation: P = I2RIf we use the equation for current from Ohm's law, I = E/R, the equation for power becomes:*See "Ugly's Electrical Reference" (SEBD0983) for additional information.Resistance
Series Circuits RT = R1 + R2 + R3 + ... RNwhere RN = resistance in the individual resistorsRT = total resistance in circuitReactance
XL = 2 π f Lwhere XL = inductive reactance in ohms f = frequency in hertzL = inductance in henriesπ = 3.1416where XC = capacitive reactance in ohms f = frequency in hertzC = capacitance in faradsπ = 3.1416Impedance
where Z = impedance in ohms R = resistance in ohmsXL = inductive reactance in ohmsXC = capacitive reactance in ohmsNote that the impendance will vary with frequency, since both XC and XL are frequency dependent. In practical AC power circuits, XC is often small and can be neglected. In that case, the formula above simplifies to:Transformer Voltage Conversion
where VS = secondary voltage VP = primary voltageNS = number of secondary turnsNP = number of primary turnsPower Factor
In mathematical terms, the power factor is equal to the cosine of the angle by which the current leads or lags the voltage. If the current lags the voltage in an inductive circuit by 60 degrees, the power factor will be 0.5, the value of the cosine function at 60 degrees. If the phase of the current in a load leads the phase of the voltage, the load is said to have a leading power factor; if it lags, a lagging power factor. If the voltage and current are in phase, the circuit has a unity power factor.Equation Summary Diagram
Three Phase Connection Systems:
Electrical Enclosure Protection = IEC
The degrees of protection provided within an electrical enclosure is expressed in terms of the letters IP followed by two numerals. Mechanical protection against impact damage is defined by an optional third numeral.Example: An IP55 enclosure protects its contents against dust and spray from water jets.Reference: DIN 40050 of July 1980, IEC 144 of 1963, IEC 529 of 1976, NF C 20-010 of April 1977Electrical Enclosure Protection - NEMA
Electrical Tables
Table 1 Electrical FormulaeTable 2 KV A of AC CircuitsTable 3 Copper Wire CharacteristicsTable 4 Single-Phase AC Motors Full Load Currents in AmperesTable 5 Three-Phase AC Motors - 80% Power Factor Full Load Current in Amperes - Induction-Type, Squirrel Cage and Wound RotorTable 6 Direct Current Motors Full Load Current in AmperesTable 7 Conduit Sizes for ConductorsTable 8 Allowable Current-Carrying Capacities of Insulated Copper ConductorsTable 9 Code Letters Usually Applied to Ratings of Motors Normally Started on Full VoltageTable 10 Identifying Code Letters on AC