Setra Systems L series Specifications download pdf (Page 87)

FREQUENTLY ASKED QUESTIONS

What is the maximum distance for BACnet MS/TP or Modbus (RS-485) communication?

BACnet MS/TP or Modbus (RS-485) can reach a distance up to 1200 meters (4000’) with data rates at

100 kbps.

One (or more) of the Phase Verification LEDs is red. What does this mean?

Any number of red lights indicates the Power Patrol meter is wired incorrectly. Review the table in

Phase Verification in Section III of this manual for a description of the indicator lights.

How is the Power Patrol meter powered?

All Power Patrol instrument is line-powered or via USB connection before installation. An internal power

supply attached between L1 and L2 provides power to the unit.

Can the Power Patrol be used to monitor single-phase loads?

The Power Patrol meter can be used to monitor single-phase loads. Refer to Section II or III for detailed

setup information.

How many Power Patrol instruments can be connected together?

Up to 127 Power Patrol meter can be connected together on a BACnet MS/TP network.

Up to 247 Power Patrol meter can be connected together on a Modbus network.

How is hexadecimal (HEX) to decimal converted?

Use the Decimal to Hexadecimal conversion table in Appendix A of this manual.

What is true RMS?

RMS stands for "Root-Mean-Square." True RMS is the power from AC voltage/current that will produce

the equivalent amount of heat in a resistor as a DC voltage/current, whether sinusoidal or not. For

example, if a resistive heating element is rated at 15 kW of heat at 240VAC RMS, then the heat would be

the same if we applied 240V of DC instead of AC. A meter without true RMS will incorrectly read

distorted waveforms. All Setra Systems meters measure true RMS.

How accurate is the Power Patrol meter?

The Power Patrol meter accuracy is 0.2% (meter only)

Can a three-phase balanced load be monitored with one CT?

This is not the best way to measure a three-phase load as it ignores imbalances in voltage and power

factor. However, if desired there is an Amp Multiplier Modbus register (44605) that can be set for

three (3), which will multiply the current by three and therefore amps, watts, VA, VARs will be 3X

greater.

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Setra Systems L series Specifications Page 87