Non-Shielded Medium Voltage Cable
National Electric Code [NEC] 2005 edition and later editions requires shielded medium voltage [MV] cables for all circuits operating above…
Zero Sequence Current Transformer
Zero Sequence Current Transformer [ZSCT] also known as Core Balance Current Transformer [CBCT] is a type of current transformer [CT]…
Percentage insulation level of medium voltage cables
Medium Voltage [MV] cable insulation is made of different variations of extruded solid or laminar (oil paper). Most common insulation…
Transformer Tap Changer: How to Select Transformer Taps?
Taps are provided on a transformer to adjust secondary voltage of power transformer for high or low voltage conditions. Common…
CURRENT UNBALANCE: CAUSES, EFFECTS AND PROTECTION
In three phase systems, current unbalance is defined as the maximum deviation of any phase current from average divided by…
THREE-PHASE TO GROUND SHORT CIRCUIT WAVEFORM
Characteristics of a Three Phase to Ground fault Following are some of the characteristic ‘signatures’ of a three phase to…
RELAY CONTACT ARCING WAVEFORM
When current flow through inductive circuit is interrupted, voltage proportional to V= L (di/dt) is produced. This voltage can be…
Current Transformer Failure Due to Capacitor Bank Discharge Current
Current Transformer (CT) failure can be due to many reasons some of which are contamination, open circuit secondary, incorrect application…
Current Transformer DC Saturation and Time to Saturate
Saturation of current transformers (CT) when carrying high magnitude current is a well-known phenomenon. Usually symmetrical fault current is used…
PARAMETERS THAT DETERMINE TRANSFORMER INRUSH CURRENT
High magnitude current lasting few power cycles during switching on a power transformer is known as transformer inrush current. Magnitude…