Limiting peak demand with IF-THEN rules on a power meter concentrator
How demand is measured, how to build staged load-shedding rules on a PMC or PMD concentrator, and a worked example with relay outputs.
Power meters, current transformers and concentrators for sub-metering, load monitoring and energy reporting.
Energy management starts with measurement. To see where energy is used, compare consumption over time or document savings, you need meters on the relevant circuits and a way to collect their data. ICP DAS supplies both: single-phase and three-phase power meters with current transformers (CTs), and concentrators that read many meters and pass the data on to SCADA, databases or cloud platforms.
The PM series power meters measure voltage, current, power, power factor and energy on single-phase and three-phase circuits. Many models are supplied with matching current transformers, sized from small branch circuits to several hundred amperes. The meters communicate over Modbus RTU, with Modbus TCP and other interfaces on selected models, so any controller, BMS or SCADA system that supports these protocols can read them.
A concentrator polls a group of meters and makes their data available in one place. The PMC series, and the PMD series with a built-in touch panel, collect data from ICP DAS meters, log it to a memory card and pass it on over Modbus TCP, MQTT, SNMP or FTP, depending on the model. Built-in IF-THEN-ELSE rules can switch loads off when demand approaches a limit. That gives a compact energy monitoring system without a separate server, or a clean data source for an existing SCADA.
Where cabling to every meter is impractical, iWSN wireless current sensing modules report to a concentrator over a wireless sensor network. For temporary measurements, a portable power monitoring kit packs the metering hardware into a carrying case.
To measure high voltages and currents with standard analog input modules, voltage attenuators and current transformers from the DNM-800 range convert the signals to levels the I/O can read safely.
Three-phase PM series meters with current transformers are fitted on the main incomer and on the feeders to each production line. A PMC concentrator reads them over RS-485, logs the values locally and sends them by MQTT to the energy reporting system. If the connection fails, the log on the memory card is sent once it is restored, so no data is lost.
We can help size meters and current transformers from a single-line diagram or a list of circuits.
The CA-SCT10P-60A-L040-3P is a split-core current transformer for energy monitoring. Its 10 mm aperture clamps around an existing conductor without disconnecting the circuit, which suits retrofit metering in distribution panels.This ordering code is supplied as a set of three CTs, each with a 4 m leader cable, and is rated for up to 60A with a 12:1 CT ratio and 1% accuracy. It is designed for the PM-2133DP, PM-3133P and PM-4324(A)P power meters.Choose this variant when your measured current falls in the 0.05A to 60A range and a 10 mm conductor aperture is sufficient. Larger conductors or higher currents need one of the other CA-SCT series ratings.ApplicationsEnergy management and power meteringCurrent monitoring in distribution panelsRetrofit submetering on existing conductors
The CA-SCT16I-100A-L080 is a split-core current transformer for measuring AC current on existing conductors. Its split design lets it be clamped around a cable without disconnecting the circuit, which suits retrofit energy monitoring. It provides one channel with a 100A rating and a Φ16mm aperture.This variant is intended for use with the iWSN and iXN series. The 8 m wire gives room to route the sensor from the conductor to the measuring device. The source data states a maximum input voltage of 500 VAC at 50/60 Hz.Accuracy is specified as 1% for the CT alone. When used with iWSN-1110X, iWSN-1131P, iWSN-750P or iWSN-757P, the stated accuracy is ±3% or ±0.3 A. The unit is RoHS and WEEE certified.ApplicationsCurrent measurement for power metering with iWSN and iXN series systemsRetrofit energy monitoring on existing conductors
CA-SCT16P-100A-L040-3P is a split-core current transformer rated for 100 A input with a 16 mm inner diameter. Its split core lets it be fitted around an existing conductor without disconnecting the circuit, which suits retrofit energy monitoring.The transformer is designed for use with the PM-2133DP, PM-3133P and PM-4324(A)P power meter series. It has a 1% accuracy rating, a 0.1 A minimum input current and a CT ratio of 20:1, with a 4 M leader cable supplied.This ordering code is sold as a set of three CTs, one per phase. Specify it when your 100 A feeder falls within the 16 mm aperture; other ratings and apertures are listed separately in the series.ApplicationsEnergy management and sub-meteringPower monitoring with PM-2133DP, PM-3133P or PM-4324(A)P power metersRetrofit current measurement on existing installations
The CA-SCT24I-200A-L080 is a single-channel split-core current transformer rated at 200A, with a Φ24mm aperture. Its split-core construction lets it be fitted around an existing conductor, which suits retrofit metering work where the circuit cannot easily be disconnected.Supplied with an 8 m lead, this CT is intended for use with the iWSN and iXN series. The maximum input voltage is 500VAC at 50/60Hz. Accuracy is rated at 1% for the CT alone, and at ±3% or ±0.3A when used with the iWSN-1110X, iWSN-1131P, iWSN-750P and iWSN-757P.Choose this variant when you need a 200A-rated CT with a Φ24mm aperture and an 8 m lead for iWSN or iXN metering installations.ApplicationsEnergy managementPower meteringCurrent monitoring on iWSN and iXN series installations
How demand is measured, how to build staged load-shedding rules on a PMC or PMD concentrator, and a worked example with relay outputs.
How to choose single-phase, three-phase or multi-circuit Modbus power meters, size the current transformers and pick Modbus RTU or TCP.
How PMC and PMD concentrators poll power meters, log to microSD, resend data after network outages and deliver it over Modbus TCP, MQTT, SNMP or FTP.
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