Rockwell Automation 1408-EMxx PowerMonitor 1000 Unit - Manual (Page 15)

PowerMonitor 1000 Unit 15
Rockwell Automation Publication 1408-IN001E-EN-P - September 2013
Maximum line to ground voltage is 347V. If line to ground voltage exceeds 347V, then potential
transformers must be used. The unit indicates voltage overrange (999.0) if an intentional or
accidental ground causes line to ground voltage in excess of 347V.
Three-phase, Three-wire Grounded B-phase, Open Delta, Direct Connect (347V AC Line-to-line
Maximum)
Maximum line to line voltage 347V. If line to line voltage exceeds 347V, then PTs must be used.
Current Sensing
Use a shorting terminal block, test block, or shorting switch you provide for current transformer
(CT) wiring to permit safely servicing connected equipment such as the power monitor without
de-energizing the power system.
Use 0.21 mm 2 (14 AWG) wiring to connect the power monitor to the shorting block. Use 0.21
mm 2 (14 AWG) or larger wire between the shorting block and the CTs depending on the length
of the circuit. Longer circuits require larger wire so that the burden of the wiring does not
overload the CT and reduce system accuracy.
When wiring a power monitor to existing CTs and metering devices, the current sensing
terminals of the power monitor must be connected in series with the CT secondary and current
sensing terminals of the existing metering devices.
Do not install overcurrent protection or non-shorting disconnecting means in CT secondary
wiring. Connect the current sensing circuit to a low-impedance earth ground at only one point.
Pay particular attention to the correct phasing and polarity of current sensing connections. The
diagrams use the dot convention to indicate transformer polarity. The dot indicates the H1 and
X1 terminals on the primary and secondary of the CT respectively. Phasing of the CTs must
correspond to the phasing of the voltage sensing connections.
The following wiring diagrams indicate typical current sensing connections to various types of
power systems.
Line
Load
Ground
L1 L2 L3 Voltage Mode = Open Delta
Fuses (by user)
PowerMonitor 1000 Unit
Distribution
Ground
V1
V2
V3
VN