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 in accordance with the applicable specifications. Testing should be performed… Read more
Feb 20, 2017 | By Edvard Csanyi
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 the related risks. Remember that “electric” locking systems are never… Read more
Feb 17, 2017 | By Edvard Csanyi
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 point being electrically displaced and the phase to neutral voltages… Read more
Feb 15, 2017 | By Edvard Csanyi
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, the intended use of the circuits and the receivers to… Read more
Feb 13, 2017 | By Edvard Csanyi
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 accelerating and decelerating requirements (time and load) Overload Determine type… Read more
Feb 10, 2017 | By Edvard Csanyi
Energy and Power
Four 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 circuit breakers between the generator set and load to be… Read more
Feb 08, 2017 | By Edvard Csanyi
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 or place probes in the ground. The method is based… Read more
Feb 06, 2017 | By Edvard Csanyi
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, NFPA 99 and other local, state, and federal codes and requirements…. Read more
Feb 03, 2017 | By Edvard Csanyi
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 motor to adjust its positioning) or to prevent plugging (sudden… Read more
Feb 01, 2017 | By Edvard Csanyi
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 as the simple single-end-fed radial system, there are other more… Read more
Jan 30, 2017 | By Edvard Csanyi
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 and phase angle, unbalanced currents in the stator windings will… Read more
Jan 27, 2017 | By Edvard Csanyi
Maintenance
Transformer exterior inspection and tests you MUST perform periodically
Periodic transformer exterior inspection (visual) reveals important condition information. For example, valves positioned incorrectly, plugged radiators, stuck temperature indicator and level gauges, and noisy oil pumps or fans. Oil leaks can often be seen which indicate a potential for oil… Read more
Jan 25, 2017 | By Edvard Csanyi
Energy and Power
Twelve golden rules for specifying and implementing a good SCADA system
A successful SCADA specification and good installation depend on choosing and utilizing proven and reliable technology, with adequate and comprehensive training of all personnel in the operation of the system. Whilst one should rightly anticipate significant development and maintenance savings by… Read more
Jan 23, 2017 | By Edvard Csanyi
Energy and Power
4 example calculations of compensation for reactive power
First, let’s say some words about basics of the reactive power in system. Reactive current arises in every electrical system. Not only large loads, but smaller loads as well require reactive power. Generators and motors produce reactive power, which causes unnecessary… Read more
Jan 20, 2017 | By Edvard Csanyi
Industrial Automation
Considerations to take into account when designing PLC ladder logic
Motor control circuits are often implemented using ladder logic. It is so called because the schematic representation of the control circuit resembles a ladder with two vertical rails and a number of horizontal rungs, as shown in Figure 1. The… Read more
Jan 18, 2017 | By Edvard Csanyi
