Modes of Operation – Variable Speed Drives
Variable speed drives are capable of operating in 4-quadrant modes of operation. When energy is transferred from the electric motor to the mechanical load, it is operating in motoring mode. …
Effect of Air Density on Equipment Physical Size
IEEE C57.13 Clause 4.2 states that the dielectric strength of air decreases as altitude decreases. The dielectric strength on air should be multiplied by the altitude correction factor provided in …
Asynchronous (Induction) Motor Data – IEC 60909
IEC 60909 provides data for asynchronous motors commonly called as induction motors. Table 4 – IEC 60909-0 Table 3 – IEC 60909-1 Clause 4.7 – IEC 60909-0 Equation 26 – …
Voltage Levels – IEC 61000-3-6
The following table provides the different voltage levels as per IEC. It is good to note that [1] is the only IEC standard that mentions about Medium voltage. All other …
Cable Rating Reduction Factor due to Harmonic Currents
The presence of harmonic current in a power system increases the current in the neutral conductor due to phase current imbalance (refer to Fig. 1b). To ascertain that the current-carrying …
IEC 61439 – Relationship between peak current and short-time current
Short-circuit withstand ratings of a switchboard or motor control centre is a measure of its ability to withstand the dynamic and thermal stresses when a fault occurs within or near …