New advances in control technology allow the ubiquitous PC to play a larger role in process interface and control.
As programmable logic controllers (PLCs) place pressure on the distributed control system (DCS) world, logic modules are placing pressure on the PLC and micro-PLC world. One new model of module can take the place of relays, latch relays, counters, and timers. It's personal computer- (PC) programmable, too. With compact dimensions, DIN rail mounting, and a low cost, this module is a contender.
The PC originally fit into the DCS world as a tool for configuring and compiling software instructions for proprietary hardware. Now, that hardware has largely been replaced by I/O devices that run directly from the PC. The controller itself no longer resides in a stand-alone rack or cabinet, but exists as a collection of software elements. Nearly all DCS vendors now run their DCS systems on popular platforms such as Unix and Windows NT. The increasing capabilities of PLCs was only one force that contributed to the virtual DCS. The truism "It's always cheaper in software" may have originally applied to the fact PLCs were replacing discrete timers and coils, but it was also evident in the demise of expensive specialized hardware that DCSs once required. The trend continues today, with the introduction of increasingly powerful virtual control devices.
A microcomputer-based 3-phase voltage monitor protects motors and other equipment from phase loss, phase reversal, low voltage, high voltage, and unbalanced voltages. It has both permissive and interlock logic so the motor will not start or run under damaging conditions, and it logs events in the order they occurred. The permissive feature also has a momentary power outage restart delay that randomly selects a time from 3 to 15 seconds. The 3-sec minimum protects against jog starts and short cycling while the utility's breaker recloses. The monitor has other selectable features, such as trip delays to prevent nuisance trips. In addition, the unit meets IEEE 587 Level B surge protection requirements.
Overload relays are becoming better all the time. Now they even come in electronic versions, which can retrofit to any motor starter. So what's the point? One electronic overload relay has a very wide range. For example, one model number can replace relays from 2A to 90A and works with a current transformer to extend its range to 700A. These relays are typically programmable for such features as trip points, trip class, and jam protection. You also have three types of restart delay to choose from. In addition, they come with RS-485 communications, so they can monitor current, voltage, and state of operation. They also can be used as remote start/stop devices. Manufacturers offer peripheral devices and software to expand the capabilities of these relays.
The most advanced feature of current-sensing relays appeared this year, with the advent of a calibrated trip-point dial that reads out in actual current. This eliminates the need for rigging a test setup when changing the set point. All calibrated instruments require periodic calibration, but this relay has features that greatly extend the calibration interval. For example, it has a precision voltage reference circuit that eliminates drift. "GO/NO GO" current sensors allow a controller to know if, indeed, an output device is actually operating. These reduce the need to guess at software timer settings while adding real-world feedback to otherwise assumptive control.
These items have appeared over the past year in EC&M's Product News section and received the highest reader response in their category.
Electronic power meter
The Power Leader electronic power meter is a full-function, revenue-class product designed for metering and power management applications. The microprocessor-based device continuously and accurately monitors and analyzes all electrical power system parameters. It fits in an S1 switchboard case, is easily retrofittable, and has options for KYZ pulse initiation and Power Leader power management system network communications. It can be programmed to meter systems up to 1200kV and 500kA.
GE Electrical Distribution & Control
The Batterylite, a microprocessor device, monitors the status of lead acid batteries, reporting on the state of charge and associated parameters. The unit provides information on the percent of charge, the state of charge trend, and 10 other conditions. An LED bar graph displays status of battery hard sulfation, equalization required, low fluid level, cell dryout in process, low and high temperature, and end of useful battery life.
Ground fault monitor
The RCM470LY-13 Ground Fault Monitor is designed to help maintain power continuity and protect personnel and equipment by providing reliable ground fault detection for grounded, high-resistance grounded, and ungrounded AC or DC systems. The insulation resistance to ground or ground leakage current is continuously monitored. A fault triggers an alarm and identifies the faulty line. The monitor automatically adjusts itself to the system capacitance and continuously monitors its connections to the system.
Electronic time switch
The new Digi 42/2 is a compact, two-channel electronic time switch with automatic daylight time changeover is intended for time-of-day control of two different circuits of lighting, heaters, fans, pumps, control circuits, or other equipment, and may be used as a one-channel DPDT time switch or two-channel SPDT time switch. In addition, the timer may be flush mounted, surface mounted, or DIN rail mounted in panels; it is available in a NEMA 1 indoor or NEMA 3R outdoor enclosure.
Control and signaling stations
This UL-listed product line is for use in U.S. Class I, Zone 1, and Zone 2 hazardous (classified) locations. Integrates explosion-protected components with the corrosion resistance of nonmetallic construction. Features include DIN rail mounted components, making field assembly a snap. A compact LED pilot light unit covers a voltage range from 12 to 254V, DC to 60 Hz. There are double pushbuttons and illuminated pushbuttons plus keyed selector switches.
Killark Electric Mfg./Hubbell
Designed for smaller circuits, the new Power-Logic Power Meter is an economical solution when the full functionality of traditional circuit monitors is not necessary. Easily mounts into a 4-in. panel meter cutout or DIN rail mounting. Monitors current, volts, kW, kvar, kVA, power factor, frequency, kWhr, kVARh, kvah, and kWhr pulse output. Voltage input up to 600V. Accurate through the 31st harmonic. The unit is small enough that it can be mounted closer to loads and directly on panelboards, motor control centers, and busway runs.
Monitor with adjustable delay
The SLD series of phase unbalance monitors protects 3-phase motors and other equipment from adverse voltage and operating conditions. When an incorrect sequence or phase loss occurs or the line voltage(s) falls outside the unbalance or under voltage adjustable settings, the relay deenergizes, and the LED indicator extinguishes. An adjustable drop-out delay is incorporated to avoid nuisance tripping.
StatusWatch, a diagnostic monitoring tool, enables immediate verification of suppression filter system operational status. Audible as well as visual notification of suppression filter system malfunction of any phase is made at unit location through battery-powered alarms and display panel illuminating lamps. In the event of system malfunction, dry contacts permit remote annunciation via the facility's building management system or remote annunicator panels.
The Model 2000 Digital Fault Recorder, a rack-mounted data acquisition system, records phase current, phase voltage, and circuit breaker operation time used for the diagnosis of system fault events. The product has the ability to obtain output automatically from a printer installed with the unit.
Cooper Power Systems
Models 158 and 158R monitors have been improved to include new features. Original features include sensing loss of phase, low-voltage, and reverse phase. The SPDT output contacts are rated for 10A up to 240VAC. The restart delay feature on the 158 R model is fixed at 4 to 6 min. New design reduces the heat generated inside the unit. It also acts to compensate for variations in ambient temperature.
The 130 PQSentry monitors single-phase line-to-neutral and neutral-to-ground 120V to 230V power for sags, swells, impulses, waveshape faults, frequency variations, harmonics to the 31st, and (optionally) temperature and current. Can transfer data to computer via external modem or RS-232 link.
Basic Measuring Instruments
The Engineer-in-a-Box provides remote monitoring and control for 110 and 220 Series UPS users. The remote monitoring components of the unit continuously monitor the UPS for specified alarms. When one of the alarms is triggered, Alarm Dial-Out will modem an alert to the user. It allows the user to access complete power information, perform diagnostic tests, and reconfigure the UPS if necessary.
The improved Model 263 3-phase monitor features monitoring for loss-of-phase, low voltage, and reverse phase. Available in three 60-Hz domestic models. The SPDT output contacts are rated for 10A at up to 240VAC. New features include an improved adjustment control allowing the installer to calibrate the unit without tools; and an optional manual reset feature allowing the unit to be reset via a switch located on the front of the unit.
The 3000 Series of digital 3-phase power monitors offers a large selection of communication options that provide direct compatibility with third-party SCADA, EMS, DCS, or PLC systems. Options include single-port and simultaneous multiport communication using Modbus, A-B Data Highway, or DNP 3.0 protocols. The Series has features from high-accuracy power and energy metering to extensive power quality analysis, data logging, and setpoint control.
Bar-digital intelligent controller
Model HI-QTBE has a 51- segment tri-color LED circular bargraph and a 6-digit numeric display with a separate alphanumeric annunciator and an LED alarm. Can be used as a simple indicator, microprocessor-based unit for managing display operation, or as an intelligent controller.
New power monitors
The PQNodes, Model Nos. 9010 and 9020, monitor power quality, power flow, and harmonics simultaneously for both the input and the output of 3-phase UPS systems. The units have from eight to 16 channels, and work with easy-to-use Power Evaluation software for Windows. The Model 9010 includes voltage screw terminals and toroid current transformers. The Model 9020 uses plug-in voltage and current inputs.
Basic Measuring Instruments
Battery performance monitor
The Battery Performance Monitor (BPM) is a discharge cycle counter that tracks the number of times the battery supplies power to the load, the duration of the event, and alarming on failing parameters by way of contact closure. Also monitors overall battery voltage, temperature, and optionally current. The self-incorporated LCD display and keyboard allow for easy user interface and system interrogation.
Resistance load control
The 10, 20, and 30A Model 18DZi single-phase power controls offer zero-fired control in a new, more compact, isolated chassis design. The new units make them interchangeable with the firm's Model 18Di series of phase angle fired power controls. Zero-fire switching provides harmonic-free, 100% power factor, proportional control for constant resistance loads.
The I/O equation station is used for measurement and control of ground water remediation systems. It takes direct analog inputs, uses common protocols, and is expandable should the application requirements grow. Unit receives direct analog input from level equipment in a well. A second analog input from a turbidity meter provides information on the, clarity of the ground water. The pump motor speed is controlled in relation to well capacity and clarity of water.
Multifunction smart relay
The Intelligent SwitchGear System (ISGS) protective relay is designed for distribution systems and retrofit applications. With the release of Software Version 3.0., the relay can monitor inputs and measurement function.
Siemens Energy & Automation
The improved Model 269 over and under 3-phase monitor observes lines for abnormal power conditions of low voltage, high voltage, phase loss, (single phasing) and phase reversal. Features a solid-state voltage and phase angle sensing circuit, which drives a SPDT output relay. Does not require a neutral connection. UL-recognized and CSA-certified.
The DLM Series of 3-phase voltage monitors stops failures of motors, compressors, pumps, etc. Improved integrated circuit design reliably senses phase loss; phase reversal; and low, high, and unbalanced voltages. Isolated 10A SPDT contacts transfer when fault is sensed.
Load bank power meter
The K514DX Power Meter monitors load banks. As a true rms meter, it displays single- and 3-phase voltages, 3-line currents, frequency, and total kW. Optional software captures data and saves it in a spreadsheet format for print analysis.
The ConSig 3-gang station includes a high illumination LED pilot light (voltage range 12V to 254VAC or DC), double push button (with two control functions in the space of one) and a key operated, emergency stop mushroom push button.
Modular, distributed I/O platform
The Flex Ex, a modular, distributed I/O platform, combines I/O modules, an intrinsic safety barrier, terminal strips, and controls. The system interfaces into an easy-to-install package. It converts standard field signals into a high-speed, intrinsically safe, deterministic communications network.
General class controller
Logo! a universal logic module, is a new class of general-purpose controller. The unit includes six digital inputs, four digital outputs, an LCD operator display unit, a 24VDC or 115/230VAC power supply, and performs up to 14 practical control functions.
Siemens Energy & Automation
This 3-in-1 digital switchboard instrument measures and displays AC volts, AC amps, frequency, and DC inputs for use with standard transducer outputs. The 4 1/2-in. unit can operate from 5A current transformers, up to 600VAC voltage inputs, and DC inputs from precision electrical transducers.