Schneider Electric PM850, PM870, PM820 Scale Factors, Scale Groups Measurement Range Scale Factor

63230-500-225A2	PowerLogicTM Series 800 Power Meter
3/2011	Chapter 6—Alarms

Scale Factors

A scale factor is the multiplier expressed as a power of 10. For example, a multiplier of 10 is represented as a scale factor of 1, since 101=10; a multiplier of 100 is represented as a scale factor of 2, since 102=100. This allows you to make larger values fit into the register. Normally, you do not need to change scale factors. If you are creating custom alarms, you need to understand how scale factors work so that you do not overflow the register with a number larger than what the register can hold. When PowerLogic software is used to set up alarms, it automatically handles the scaling of pickup and dropout setpoints. When creating a custom alarm using the power meter’s display, do the following:

•Determine how the corresponding metering value is scaled, and

•Take the scale factor into account when entering alarm pickup and dropout settings.

Pickup and dropout settings must be integer values in the range of -32,767 to +32,767. For example, to set up an under voltage alarm for a 138 kV nominal system, decide upon a setpoint value and then convert it into an integer between -32,767 and +32,767. If the under voltage setpoint were 125,000 V, this would typically be converted to 12500 x 10 and entered as a setpoint of 12500.

Six scale groups are defined (A through F). The scale factor is preset for all factory- configured alarms. Table 6–2 lists the available scale factors for each of the scale groups. If you need either an extended range or more resolution, select any of the available scale factors to suit your need. Refer to “Changing Scale Factors” on page 91 of

Appendix C—Using the Command Interface.

Table 6–2: Scale Groups

Scale Group	Measurement Range	Scale Factor
	Amperes
	0–327.67 A	–2
Scale Group A—Phase Current	0–3,276.7 A	–1
	0–32,767 A	0 (default)
	0–327.67 kA	1
	Amperes
	0–327.67 A	–2
Scale Group B—Neutral Current
	0–3,276.7 A	–1
	0–32,767 A	0 (default)
	0–327.67 kA	1
	Voltage
	0–3,276.7 V	–1
Scale Group D—Voltage
	0–32,767 V	0 (default)
	0–327.67 kV	1
	0–3,276.7 kV	2
	Power
	0–32.767 kW, kVAR, kVA	–3
	0–327.67 kW, kVAR, kVA	–2
Scale Group F—Power kW, kVAR, kVA	0–3,276.7 kW, kVAR, kVA	–1
	0–32,767 kW, kVAR, kVA	0 (default)
	0–327.67 MW, MVAR, MVA	1
	0–3,276.7 MW, MVAR, MVA	2
	0–32,767 MW, MVAR, MVA	3

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