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© 2011 Schneider Electric. All Rights Reserved.
63230-500-225A2 PowerLogic
TM
Series 800 Power Meter
3/2011 Chapter 6—Alarms
49
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 10
1
=10; a multiplier of 100 is represented as a
scale factor of 2, since 10
2
=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
Scale Group A—Phase Current
Amperes
0–327.67 A –2
0–3,276.7 A –1
0–32,767 A 0 (default)
0–327.67 kA 1
Scale Group B—Neutral Current
Amperes
0–327.67 A –2
0–3,276.7 A –1
0–32,767 A 0 (default)
0–327.67 kA 1
Scale Group D—Voltage
Voltage
0–3,276.7 V –1
0–32,767 V 0 (default)
0–327.67 kV 1
0–3,276.7 kV 2
Scale Group F—Power kW, kVAR, kVA
Power
0–32.767 kW, kVAR, kVA –3
0–327.67 kW, kVAR, kVA –2
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