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When medium voltage autotransformer (RVAT) motor starters fail, also referred to as a Korndorfer starter, the results are almost always catastrophic, particularly ones in which there is no clear failure to the core or tap-to-tap but just layer-to-layer deep down in the windings. An offshore platform is used as an example to explain the techniques and to discuss site specific solutions that are based...
The application of speed control using adjustable speed drives (ASDs) in industrial applications that contain fans and pumps enables improved energy efficiency and conservation and offers improved process control. However, the success of the application in terms of energy conservation and improved process control depends upon tempering enthusiasm with disciplined logic in order to maximize the benefits...
Motor management relays can enhance protection by locking out a motor after a trip or a stop until the motor has cooled enough to restart the motor. This feature enhances motor protection because it insures the start will not cause the motor temperature to exceed the thermal damage curve. As with any protective relay setting, correct settings are important, but with restart protection they can be...
When selecting a control valve for a pulp and paper application, it is important to have a basic understanding of control valve sizing and selection and how it affects control valve performance. Optimizing control valve selection can improve loop dynamics and alleviate problems such as cavitation, flashing, and noise. This paper will review guidelines and apply industry standard sizing models to applications...
Ground faults in generator stator and field/rotor circuits are serious events that can lead to damage, costly repair, extended outage and loss of revenue. This paper explores advances in field/rotor circuit ground fault and stator ground fault protection. [1] These advanced protection strategies employ AC injection, ground differential protection and the use of hybrid grounding to reduce both internal...
The application of STATCOM or STATCON is common in transmission systems—the device has a capability of P-Q control in 4 quadrants. DSTATCOM (for distribution systems) and DVR (Dynamic Voltage Regulator) are somewhat synonymous. The paper describes a unique distribution system with three in-plant generators and an interconnection to weak utility system at 44 kV; the three-phase short-circuit level...
Demanding machine up-time goals can limit the amount of time available for proper preventative maintenance practices. In addition, the drive to downsize maintenance staff of production facilities decreases the available man-hours. If preventative maintenance is not taken seriously, action items may fall behind or become neglected leaving opportunities for more issues to arise in time. This leads to...
This paper is a case study outlining the selection and installation of a new medium-voltage motor control center (MCC) installed at a major process industrial facility in the USA. The new motor control center was installed as a part of a system expansion addition of four new pumps included in a bleach plant modernization project. The installation included a bus connection to an existing vintage medium-voltage...
High performance industrial drives typically do not simultaneously minimize machine losses and achieve fast transient torque dynamics. This paper introduces a deadbeat-direct torque and flux control (DB-DTFC) algorithm that achieves decoupled control of air gap torque and stator flux linkage using an inverse machine model. Stator flux linkage serves as a separate degree-of-freedom to manipulate machine...
Owners, operators, installers, and maintainers of industrial and commercial electric power systems and equipment, along with design consultants and manufacturers, should be concerned with the electrical safety aspects associated with these systems and equipment. Electrical safety must be an integral part of all electrical equipment and systems design, installation, and maintenance. An in-depth knowledge...
Laboratory tests were carried out on seven voltage monitoring relays to determine their operational characteristics. The objective was to gain an understanding of the impact of identical power quality events on different voltage monitors commonly installed on utilization equipment. The tests focused on typical monitors found on a local utility's customers' equipment including device models that have...
The paper describes a selective high resistance grounding (HRG) system for large industrial facility with two in-plant generators in cogeneration mode and two utility transformers. In a 5-step coordination using sensitive ground fault non-directional and directional relays, ground fault throughout the distribution system are cleared with a maximum pickup setting of 6A, time delay of 0.25s. A major...
DC systems are not included in IEEE 1584 and NFPA 70E does not provide much guidance regarding this topic. Therefore, there is currently no established method for power plant operators to determine the potential energy level that personnel could be exposed to when changing collector brushes during generator operation should an arc form between the positive and negative slip rings or between a slip...
Much attention has been given to mitigation of the arc flash hazard using various fast protection schemes such as light sensing and differential relaying. This paper examines several techniques and quantifies each technique with model systems. The model system consists of several Thevenin equivalent circuits which produces different maximum fault current levels. These Thevenin equivalent circuits...
A previously-presented PPIC paper reported the results of use of alternate testing technology employing a magnetron device to apply a magnetic field, external to the VI (vacuum interrupter), to enable estimation of vacuum integrity. This process is known as MAC (magnetron atmosphere condition) testing. Results were reported from one mill outage in 2013, encompassing approximately 50 VI's. The data...
This paper describes the sequence of events that lead to a near-fatal accident on a 4.16 kV power system that was undergoing maintenance. All parties concerned believed the equipment was properly locked out and tagged out of service. A breakdown in communication between the equipment owner/scheduler, the primary contractor and a subcontractor allowed a service technician to enter an energized switchgear...
This paper is a summary of a case study of a pulp and paper mill that had greater than 100 solidly grounded substations. In order to reduce the likelihood of an arc flash, they were changes to a high resistance grounded system. This change increased the safety and reliability of the facility as well as reduce arc flash incidences in the low-voltage substations.
This paper expands on the work of a previous paper that presented the possibility of a significant reduction of incident energy on the secondary of medium voltage to low voltage (MV-LV) transformers with the combination of a high speed grounding switch (HSGS) and traditional MV current limiting (CL) E-Rated fuses. It was shown that when the HSGS is applied at a location between the E-rated fuse load...
Current-differential principles are well known and commonly used for protection of medium and large size transformers, large motors, medium voltage (MV) generators, medium and high voltage buses, and any type of important power equipment with measurable input and output currents. However, is it practical to protect low voltage distribution buses using differential protection? This paper will describe...
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