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Nexus
1250 /1252
High Performance SCADA Monitor
Installation & Operation Manual
Version 1.25
November 13, 2006
Doc # E107706 V1.25
Electro Industries/GaugeTech
1800 Shames Drive
Westbury, New York 11590
Tel: 516-334-0870 Fax: 516-338-4741
Sales@electroind.com www.electroind.com
“The Leader in Web Accessed Power Monitoring and Control”
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Electro Industries/GaugeTech Doc # E107706 V1.25
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Nexus 1250/1252 Installation and Operation Manual Revision 1.25 Published by: Electro Industries/GaugeTech 1800 Shames Drive Westbury, NY 11590 All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or information storage or retrieval systems or any future forms of duplication, for any purpose other than the purchaser’s use, without the expressed written permission of Electro In
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Customer Service and Support Customer support is available 9:00 am to 4:30 pm, eastern standard time, Monday through Friday. Please have the model, serial number and a detailed problem description available. If the problem concerns a particular reading, please have all meter readings available. When returning any merchandise to EIG, a return materials authorization number is required. For customer or technical assistance, repair or calibration, phone 516-334-0870 or fax 516-338-4741. Product
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About Electro Industries/GaugeTech Electro Industries/GaugeTech was founded in 1973 by Dr. Samuel Kagan. Dr. Kagan’s first innovation, an affordable, easy-to-use AC power meter, revolutionized the power-monitoring field. In the 1980s Dr. Kagan and his team at EIG developed a digital multifunction monitor capable of measuring every aspect of power. EIG further transformed AC power metering and power distribution with the Futura+ device, which supplies all the functionality of a fault recorder,
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Electro Industries/GaugeTech Doc # E107706 V1.25 iv
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Table of Contents Chapter 1: Three-Phase Power Measurement 1.1: Three-Phase System Configurations . . . . . . . . . . . . . . . . . . . . .1-1 1.1.1: Wye Connnection . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1 1.1.2: Delta Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3 1.1.3: Blondell’s Theorem and Three Phase Measurement . . . . . . . . . . . . .1-4 1.2: Power, Energy and Demand . . . . . . . . . . . . . . . . . . . . . . . .1-6 1.3: Reactive Energy and P
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Chapter 5: Communication Wiring 5.1: Communication Overview . . . . . . . . . . . . . . . . . . . . . . . . .5-1 5.2: RS-232 Connection-Nexus Meter to a Computer . . . . . . . . . . . . . . .5-5 5.3: RS-485 Wiring Fundamentals (with RT Explanation) . . . . . . . . . . . . . .5-5 5.4: RS-485 Connection- Nexus Meter to a Computer or PLC . . . . . . . . . . . .5-8 5.5: RJ-11 (Telephone Line) Connection- Nexus with Internal Modem Option to PC . . 5-8 5.6: RJ-45 Connection- Nexus with Internal Networ
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8.3: TOU Prior Season and Month . . . . . . . . . . . . . . . . . . . . . . .8-2 8.4: Updating, Retrieving and Replacing TOU Calendars . . . . . . . . . . . . . .8-2 8.5: Daylight Savings and Demand . . . . . . . . . . . . . . . . . . . . . . .8-2 Chapter 9: Nexus External I/O Modules 9.1: Hardware Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-1 9.1.1: Port Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-2 9.2: Installing Nexus External I/O Modules . . . .
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12.7: Log Viewer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12-7 12.8: Performance Notes . . . . . . . . . . . . . . . . . . . . . . . . . . .12-8 Appendix A: Transformer Loss Compensation Excel Spreadsheet with Examples A.1: Calculating Values . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-1 A.2: Excel Spreadsheet with Example Numbers . . . . . . . . . . . . . . . . .A-1 Glossary of Terms Electro Industries/GaugeTech Doc #: E107706 V1.25 VIII
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Chapter 1 Three-P Phase Power Measurement This introduction to three-phase power and power measurement is intended to provide only a brief overview of the subject. The professional meter engineer or meter technician should refer to more advanced documents such as the EEI Handbook for Electricity Metering and the application standards for more in-depth and technical coverage of the subject. 1.1: Three-P Phase System Configurations Three-phase power is most commonly used in situations where
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Three-phase voltages and currents are usually represented with a phasor diagram. A phasor diagram for the typical connected voltages and currents is shown in Figure 1.2. Fig 1.2: Phasor Diagram Showing Three-phase Voltages and Currents o The phasor diagram shows the 120 angular separation between the phase voltages. The phase-to- phase voltage in a balanced three-phase wye system is 1.732 times the phase-to-neutral voltage. The center point of the wye is tied together and is typically grounde
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1.1.2: Delta Connection Delta connected services may be fed with either three wires or four wires. In a three-phase delta service the load windings are connected from phase-to-phase rather than from phase-to-ground. Figure 1.3 shows the physical load connections for a delta service. Phase C Phase A Phase B Figure 1.3: Three-Phase Delta Winding Relationship In this example of a delta service, three wires will transmit the power to the load. In a true delta service, the phase-to-ground
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Fig 1.5: Phasor Diagram Showing Three-phase, Four-wire Delta Connected System 1.1.3: Blondell’s Theorem and Three Phase Measurement In 1893 an engineer and mathematician named Andre E. Blondell set forth the first scientific basis for poly phase metering. His theorem states: If energy is supplied to any system of conductors through N wires, the total power in the system is given by the algebraic sum of the readings of N wattmeters so arranged that each of the N wires contains one curre
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single three-phase reading. Some digital meters calculate the individual phase power values one phase at a time. This means the meter samples the voltage and current on one phase and calculates a power value. Then it samples the second phase and calculates the power for the second phase. Finally, it samples the third phase and calculates that phase power. After sampling all three phases, the meter combines the three readings to create the equivalent three-phase power value. Using mathematical a
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1.2: Power, Energy and Demand It is quite common to exchange power, energy and demand without differentiating between the three. Because this practice can lead to confusion, the differences between these three measurements will be discussed. Power is an instantaneous reading. The power reading provided by a meter is the present flow of watts. Power is measured immediately just like current. In many digital meters, the power value is actually measured and calculated over a one second inte
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Time Interval Accumulated Power (kW) Energy (kWh) (Minute) Energy (kWh) 1 30 0.50 0.50 2 50 0.83 1.33 3 40 0.67 2.00 4 55 0.92 2.92 5 60 1.00 3.92 6 60 1.00 4.92 7 70 1.17 6.09 8 70 1.17 7.26 9 60 1.00 8.26 10 70 1.17 9.43 11 80 1.33 10.76 12 50 0.83 12.42 13 50 0.83 12.42 14 70 1.17 13.59 15 80 1.33 14.92 Table 1.2: Power and Energy Relationship Over Time As in Table 1.2, the accumulated energy for the power load profile of Figure 1.7 is 14.92 kWh. Demand is also a time-based value. The dema
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Figure 1.8 shows another example of energy and demand. In this case, each bar represents the energy consumed in a 15-minute interval. The energy use in each interval typically falls between 50 and 70 kWh. However, during two intervals the energy rises sharply and peaks at 100 kWh in interval number 7. This peak of usage will result in setting a high demand reading. For each interval shown the demand value would be four times the indicated energy reading. So interval 1 would have an associate
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I R V Angle θ I X I Figure 1.9: Voltage and Complex The voltage (V) and the total current (I) can be combined to calculate the apparent power or VA. The voltage and the in-phase current (IR) are combined to produce the real power or watts. The volt- age and the quadrature current (IX) are combined to calculate the reactive power. The quadrature current may be lagging the voltage (as shown in Figure 1.9) or it may lead the voltage. When the quadrature current lags the vol
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result, it does not include the impact of harmonic distortion. Displacement power factor is calculated using the following equation: Displacement PF = cos θ, where θ is the angle between the voltage and the current (see Fig. 1.9). In applications where the voltage and current are not distorted, the Total Power Factor will equal the Displacement Power Factor. But if harmonic distortion is present, the two power factors will not be equal. 1.4: Harmonic Distortion Harmonic distortion is primaril
