John A. Kay

Methods for the control of large medium voltage motors; application considerations and guidelines

Starting and control methods available for medium voltage induction motors, (2.4 kV-7.2 kV), in the petrochemical industry are continually changing in terms of application considerations due to the evolution of available products and changing characteristics of the machine and processes. This paper summarizes several common methods and provides application guidelines for proper selection considering the distribution system, driven equipment, speed-torque issues, process requirements, starter method limitations and economics. Starting means reviewed include medium voltage soft starters, variable frequency drives, and autotransformer, capacitor, reactor, captive transformer, across the line controllers as well as fluid couplers.

The Smart Solution for the Prediction of Slowly Developing Electrical Faults in MV Switchgear Using Partial Discharge Measurements

An electrical fault in switchgear results in interruption of power supply, damage to equipment, and poses a hazard to personnel. This paper focuses on the detection of slowly developing faults leading to internal arc, using online monitoring technologies in medium-voltage switchgear. Unconventional radio-frequency (RF) techniques for discharge measurement are highly attractive but have not been widely applied in the industry due to their ineligibility to quantify actual discharge. On the basis of various benefits, a new application of a differential electric field ( D-dot) sensor for partial-discharge (PD) measurements has been introduced in this paper. The reliability of the sensor has been confirmed through comparison with a commercial high- frequency current transformer. An attempt has been made to quantify the apparent charge of online PD measurements. The energy of signal captured by the D-dot sensor has been compared with the apparent charge quantity calculated from current pulse measured by the conventional method. A second degree polynomial relation exists between the cumulative energy and apparent charge. It has been shown that when apparent charge is plotted against the cumulative energy of the RF signal for a number of pulses, defects can be separated on the basis of cluster positions within the scatter plot.

Installation and Application Considerations of Arc Resistant Medium Voltage Control Equipment

Improved medium voltage (MV) control equipment designs, including enhanced structural protection systems, have continued to evolve in support of improved personnel protection. Recent changes to some standards, such as the NFPA-70E; have emphasized the need to look for improved safety compliance to mitigating the risks associated with the operation and maintenance of electrical equipment. The requirements for employee safe work practices have all targeted reducing the risks of electrical arc hazards. However, arcs accompanied by explosions continue to occur in electrical systems. Factors such as inappropriate human interaction with the equipment, equipment malfunctions because of misuse or lack of regular maintenance or unforeseen events continue to contribute to the unexpected release of explosive electrical energy in the workplace. New arc resistant MV control equipment designs provide an additional level of protection if properly installed and applied. This paper will outline the added benefits of arc resistant equipment along with the details surrounding the appropriate installation and site application considerations when arc resistant MV control products are being considered. Also included is a case history where arc resistant medium voltage motor control equipment was installed at a production facility of a large North American chemical company.

Testing and Certification of Medium Voltage Control Centers to Arc Resistant Standards

Improved medium voltage control equipment designs, including enhanced structural protection systems, have continued to evolve in support of improved personnel protection. Recent changes to some standards, such as the NFPA-70E, have emphasized the need to look for improved safety compliance to mitigating the risks associated with the operation and maintenance of electrical equipment. The requirements for employee safe work practices have all targeted reducing the risks of electrical arc hazards. However arcs accompanied by explosions continue to occur in electrical systems. Factors such as inappropriate human interaction with the equipment, equipment malfunctions as a result of misuse or lack of regular maintenance or unforeseen events continue to contribute to the unexpected release of explosive electrical energy in the workplace. This paper outlines the details surrounding the testing of medium voltage (MV) control center equipment to permit it to be certified to present arc resistant standards. The intent of this paper is to improve the understanding of the dynamics of an arc fault and how new arc resistant equipment designs can reduce personnel from exposed to electrical arc hazards in industrial settings

Benefits of IEC 61850 standard for power monitoring and management systems in forest products industries

The IEC 61850 standard, using Ethernet as its primary communication architecture, can be utilized in a fashion to significantly benefit pulp and paper process users. While IEC 61850 defines three types of communication: Generic Object Oriented Substation Event (GOOSE), Manufacturing Message Specification (MMS), and Sampled Measured Values (SMV), this paper will focus on the benefits of Manufacturing Message Specification (MMS) communications. Utilizing the IEC 61850 communications, measurands can be gathered into a central system. This repository of data can be accessed by multiple users anywhere on the factory or enterprise networks. This data can be used for energy management, load shedding, and complete power system monitoring and control. Additionally, IEC 61850 allows for the command and control, or actuation of protection equipment in the system; therefore reducing start time between failures while also increasing safety levels as remote actuation does not require local access and the use of Personal Protection Equipment (PPE). In modern Supervisory Control and Data Acquisition (SCADA) systems, the measurands and targets are visually displayed providing a visual representation of the electrical and process control system performance. This paper will discuss the merits of constructing an IEC 61850 based monitoring and management solution for forest products and pulp and paper process industries.

Intelligent motor control, a definition and value add to process control

As technology continues to drive innovations, heavy industrial enterprises must continue to keep pace to remain competitive in and ever changing marketplace. The trend of technology is to replace systems of yesterday with higher performance, low-cost, option rich devices that shorten the return on investment and offer more flexibility. As control system technology continues to evolve, we see this same migration in the way many functions are being increasingly distributed to smarter, more granular, control system components capable of performing localized operations that were once the responsibility of a central or master controller. The integration of intelligent devices, device level networks, and interrogation software into medium voltage (MV) and low voltage (LV) motor control centers is a good example of how technology can deliver improved diagnostics, early warnings for increased system reliability, design flexibility, simplified wiring and provide another level of personnel safety for process industries. This paper focuses on technology integration, intelligent devices and device level information collection to provide convergence of control and information for plant wide optimization.

Understanding infrared windows and their effects on infrared readings

The use of infrared (IR) windows in electrical control and distribution equipment has become increasingly more prevalent over recent years. With increased focus on electrical safety and the widespread adoption by industry of NFPA-70E, IR systems are increasingly more popular. However, using IR windows with thermal imaging cameras introduces a serious problem when it comes to predictive maintenance, i.e., measurement accuracy. This paper discusses the effects of various materials used in IR windows for noncontact temperature measurement. Varying degrees of measurement inaccuracy and methods to correct for these inaccuracies with various thermal imagers is covered. Other factors outlined will include the factors affecting IR transmission through various IR window materials used in various practical electrical inspection applications. Moreover, how these various materials affect the accuracy of the readings and ways to correct these various transmission losses will be also addressed. The conclusions provide the details for a successful preventive and predictive maintenance program when using various thermal imagers along with different types of IR windows.

Maximizing protection by minimizing arcing times in medium voltage systems

Arcing faults in the forest product industries are real risks that often lead to severe injuries and fires. From an economic point of view, the consequences due to direct and indirect costs can be extremely high as well. There are various opportunities to prevent arcing faults, but faults cannot be totally eliminated. This is why several approaches to mitigate the consequences of arcing faults have been introduced, particularly in the last decade. Several manufacturers have started to produce arc-flash protection relays based on optical detection of light energy from an arc event. In most applications, the light information is confirmed by overcurrent information before a trip command is initiated to an upstream current-breaking device. The tripping of a circuit breaker, for instance, occurs in only a few milliseconds. In most cases, this seems to be the state-of-the-art technology leading to very reasonable incident energy levels. However, it is essential to be able to minimize not only the thermal impact but also the pressure wave. This paper investigates technology aimed at maximizing the protection for the pressure wave.

Protection at the speed of light: Arc-flash protection combining arc flash sensing and arc-resistant technologies

One of the most critical aspects of reducing both personnel injury and equipment damage is through the reduction of the energy available to an arcing fault. The initiation of a trip and the clearing time (opening) of any upstream device is a critical component in the reduction of the resultant arc flash incident energy. Combining technologies that detect and interrogate both arc flash and the associated arc current signatures in combination with arc resistant switchgear or controlgear, can provide a coordinated solution for controlling the level of incident energy at various points within the distribution network. Hybrid systems of this type provide the highest level of personnel protection, along with comprehensive equipment protection, as detection and initiation of tripping is implemented faster than with conventional relaying techniques alone. The reduction of the overall trip time can reduce equipment collateral damage, reconditioning time and lost productivity resulting from downtime. These types of coordinated systems will also lower the personal protective equipment (PPE) requirements based on incident energy. This paper compares several systems including conventional overcurrent protection, zone selective and various light and current sensing systems.

The use of infrared viewing systems in electrical control equipment

The use of infrared imaging devices for monitoring the health of electrical equipment is well known and widely accepted in todays industry. Millions of dollars are saved each year in reduced unscheduled downtime and lower capital costs relating to repair of failed equipment. Due to the physics involved in the transmission of infrared radiation, tradition IR scanning methodology involved the removal of outer doors and covers of the energized equipment to provide a direct line of sight to target. With the widespread adoption of NFPA70E and the recent OSHA CFR29 requirements, the exposure of personnel to live electrical equipment is no longer acceptable. This paper explores the difficulties presented to todays infrared maintenance personnel with regard to electrical equipment. The paper presents options for the use of infrared viewing systems and techniques designed to make infrared predictive maintenance faster, safer and more cost effective