Maintenance
Performing power factor test on dry-type transformer during commissioning
The power factor test is a maintenance test used to determine the insulation system dielectric power loss by measuring the power angle between an applied AC voltage and the resultant… Read more
Mar 01, 2017 | By Edvard
Electric Motor
Basic electrical design of a PLC panel (Wiring diagrams)
It is uncommon for engineers to build their own PLC panel designs (but not impossible of course). For example, once the electrical designs are complete, they must be built by… Read more
Feb 27, 2017 | By Edvard
Low Voltage
Measurement of N–PE loop resistance in TN, TT and IT systems
Up-to-date test instruments, with built in modern electronics, can measure loop resistance even between the neutral N and protection PE conductors in spite of possible high currents in the neutral… Read more
Feb 24, 2017 | By Edvard
Energy and Power
Do you know what ground potential rise is? It’s really important.
First of all, ground potential rise is very important and very dangerous event. The grounding engineer will be required to develop safety systems to protect any personnel working where ground… Read more
Feb 22, 2017 | By Edvard
Cables
Guidelines for high potential (Hi-Pot) DC testing of medium voltage cables
This technical article provides general guidelines for high potential “Hi-Pot” DC testing of MV power cables. All tests made following cable installation and during the warranty period must be performed… Read more
Feb 20, 2017 | By Edvard
Energy and Power
5 good examples of locking out HV/MV/LV structures and equipment
In all cases the choice of locks and safety positions requires prior analysis of the locking sequence to be applied in order to correctly define the requirement and clearly identify… Read more
Feb 17, 2017 | By Edvard
Energy and Power
How a three-phase power transformer responds to harmonics
The way in which a three-phase transformer responds to harmonics depends on the connection configuration used. For a star-star configuration, any imbalance in the phase currents results in the star… Read more
Feb 15, 2017 | By Edvard
Electric Motor
Detailed calculation of currents and power according to the type of load
Currents and power analysis are key factors in any design or redesign of an installation they will enable the source(s) to be sized according to the purpose of the installation,… Read more
Feb 13, 2017 | By Edvard
Electric Motor
Practical checks for motor selection on AC adjustable speed drive systems
Important checks to consider in the motor selection for AC adjustable speed drive system: Determine motor enclosure requirements Determine motor torque and speed requirements: Operating speed range Breakaway torque Determine… Read more
Feb 10, 2017 | By Edvard
Energy and Power
4 typical designs for connecting generator set(s) to the low voltage system
Many different system designs are possible, but for highest reliability, systems are typically configured so that generator set(s) are connected at low voltage, with the minimum number of transformers and… Read more
Feb 08, 2017 | By Edvard
Energy and Power
The easiest way to measure ground resistance using clamp meter, but be carefull!
The ground clamp meter / tester is an effective and time-saving tool when used correctly because the user does not have to disconnect the ground system to make a measurement… Read more
Feb 06, 2017 | By Edvard
Energy and Power
Single line diagrams of emergency and standby power systems with automatic transfer switch (ATS)
Emergency and standby power systems are generally designed into the over-all electrical system for one of the following two reasons: Legal Requirements – As required by the NEC, NFPA 101,… Read more
Feb 03, 2017 | By Edvard
Electric Motor
Ladder logic for special motor control circuits – jogging and plugging
Ladder logic is often used to implement various motor control circuits. Beside standard motor control circuits, there are also special control circuits designed to allow jogging (brief energization of the… Read more
Feb 01, 2017 | By Edvard
Protection
The essentials of directional overcurrent protection in electrical power grid
Why do we use directional overcurrent protection? When does fault current direction become important? Well, electrical power grid comprises a network of power stations, substations and transmission lines. As well… Read more
Jan 30, 2017 | By Edvard
Electric Motor
The influence of voltage unbalance on NEMA motor performance
Voltage unbalance can be more detrimental than voltage variation to motor performance and motor life. When the line voltages applied to a polyphase induction motor are not equal in magnitude… Read more
Jan 27, 2017 | By Edvard
