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Abstract
PMI offers the ability to monitor with two styles of voltage input connections to provide the user with the most flexibility when troubleshooting power quality issues. This white paper describes the proper hookup connections for common mode input style PMI power analyzers.
The VIP, iVS-3, and iVS-3/600P have differential voltage inputs where the Eagle, Revolution, and Vision have common mode voltage inputs. Although the differential and common mode voltage inputs can monitor the same circuit types; the connections on the circuit differ slightly. In order to fully understand the circuit hookup diagram, some circuit theory will be reviewed.
Common Mode Or Single-Ended Inputs
Common mode inputs, as shown in Figure 1, only provide one input for each channel and share a “common” point between channels.
Figure 1. Common mode input circuit diagram
Depending on the circuit type, the common point could either be neutral or floating. In the case of the WYE circuit, the common point is the neutral connection. All voltage measurements are referenced to neutral and considered to be phase to neutral measurements. In the case of the Delta circuit, the common point is floating. All measurements are referenced to the corresponding phase voltage and the DELTA voltages are calculated.
Differential Voltage Inputs
Differential inputs (Figure 2) provide two inputs for each channel that respond to the signal difference between them.
Figure 2. Differential input circuit diagram
Differential inputs do not share a common point between the channels of the recorder. The voltage measurements in any circuit type are the difference between channel connections. Since differential input recorders do not share a “common” point, they could be used to monitor two circuits that are completely isolated.
Circuit Types
Depending on the distribution network and required service voltages, there could be a number of circuit types to monitor. Below are the circuit diagrams and a brief description on the proper connection sequence for the common circuit types found in most power systems.
Three-phase Wye
There are 9 connections associated with the 3-phase WYE system including the current channels as shown in Figure 3.
Figure 3. Three-phase WYE
CH1 (A) voltage and current, CH2 (B) voltage and current, CH3 (C) voltage and current, and CH4, which is optional. Since the 3-phase WYE system has a neutral connection, the white wire neutral connection on the recorder needs to be made at this point. As shown in Figure 3, the white wire is connected to the common point and is all that is required to make up this connection. The line connections are the remaining points that need to be connected in a WYE fashion. As shown in Figure 3, the CH1 or A phase connection is the black wire, the CH2 or B phase connection is the red wire, the CH3 or C phase connection is the blue wire, and the CH4 (optional channel) is the yellow wire. The current channels are connected respectively with the voltage channel connections as shown in Figure 3. In order to monitor with the WYE connected circuit type, the recorder must be initialized to WYE.
Three-phase Delta
There are 9 connections associated with the 3-Phase Delta system including the current channels. CH1 (A) voltage and current, CH2 (B) voltage and current, CH3 (C) voltage and current and CH4 which is optional. Since the 3-Phase Delta system has no neutral connection, the white wire neutral connection on the recorder needs to be made on the CH2 (B) phase channel. As shown in Figure 4, the white wire is connected to the CH2 (B) phase and is all that is required to make up this connection.
Figure 4. Three-phase Delta
The line connections are the remaining points that need to be connected in a Delta fashion. As shown in Figure 4, the CH1 or A phase connection is the black wire, the CH2 or B phase connection is the red wire, the CH3 or C phase connection is the blue wire, and the CH4 (optional channel) is the yellow wire. The current channels are connected respectively with the voltage channel connections as shown in Figure 4. In order to monitor with the 3-Phase Delta connected circuit type, the recorder must be initialized to 3 Wire Delta.
NOTE: The “common” connection or white wire has no reference in the phase to phase measurements in a 3-Phase Delta system. The “common” is only used to power the recorder.
Open Delta
The Open Delta uses the same connection scheme and initialization as the 3 Wire Delta circuit. There are 9 connections associated with the Open Delta System including the current channels. CH1 (A) voltage and current, CH2 (B) voltage and current, CH3 (C) voltage and current, and CH4 which is optional. Since the Open Delta System has no neutral connection, the white wire neutral connection on the recorder needs to be made on the CH2 (B) phase channel. As shown in Figure 5, the white wire is connected to the CH2 (B) phase and is all that is required to make up this connection. The line connections are the remaining points that need to be connected in a Delta fashion. As shown in Figure 5, the CH1 or A phase connection is the black wire, the CH2 or B phase connection is the red wire, the CH3 or C phase connection is the blue wire, and the CH4 (optional channel) is the yellow wire.
Figure 5. Open Delta
The current channels are connected respectively with the voltage channel connections as shown in Figure 5. In order to monitor with the Open Delta connected circuit type, the recorder must be initialized to 3 Wire Delta.
NOTE: The “common” connection or white wire has no reference in the phase-to-phase measurements in a Open Delta system. The “common” is only used to power the recorder.
Four Wire Delta
There are 9 connections associated with the 4 Wire Delta System including the current channels. CH1 (A) voltage and current, CH2 (B) voltage and current, CH3 (C) voltage and current, and CH4 which is optional. Since the 4 Wire Delta System has a neutral connection, the white wire neutral connection on the recorder needs to be made at this point. As shown in Figure 6, the white wire is connected to the common point and is all that is required to make up this connection.
Figure 6. Four Wire Delta
The line connections are the remaining points that need to be connected in a 4 Wire Delta fashion. As shown in Figure 6, the CH1 or A phase connection is the black wire, the CH2 or B phase connection is the red wire, the CH3 or C phase connection is the blue wire, and the CH4 (optional channel) is the yellow wire. The current channels are connected respectively with the voltage channel connections as shown in Figure 6. In order to monitor with the 4 Wire Delta connected circuit type, the recorder must be initialized to 4 Wire Delta.
Two Element Delta
The Two Element Delta uses the same connection scheme and initialization as the 3 Wire Delta circuit. There are 8 connections associated with the Two Element Delta system including the current channels. CH1 (A) voltage and current, CH2 (B) voltage, CH3 (C) voltage and current, and CH4 which is optional. Since the Two Element Delta system has no neutral connection, the white wire neutral connection on the recorder needs to be made on the CH2 (B) phase channel. As shown in Figure 7, the white wire is connected to the CH2 (B) phase and is all that is required to make up this connection.
Figure 7. Two Element Delta
The line connections are the remaining points that need to be connected in a Two Element Delta fashion. As shown in Figure 7, the CH1 or A phase connection is the black wire, the CH2 or B phase connection is the red wire, the CH3 or C phase connection is the blue wire, and the CH4 (optional channel) is the yellow wire. The current channels are connected respectively with the voltage channel connections as shown in Figure 7. In order to monitor with the Two Element Delta connected circuit type, the recorder must be initialized to 3 Wire Delta.
NOTE: The “common” connection or white wire has no reference in the phase-to-phase measurements in a Two Element Delta system. The “common” is only used to power the recorder.
2 ½ Element Wye
There are 8 connections associated with the 2 ½ Element WYE system including the current channels. CH1 (A) voltage and current, CH2 Current, CH3 (C) voltage and current, and CH4 which is optional. Since the 2 ½ Element WYE system has a neutral connection, the white wire neutral connection on the recorder needs to be made at this point. As shown in Figure 8, the white wire is connected to the common point and is all that is required to make up this connection.
Figure 8. 2 ½ Element WYE
The line connections are the remaining points that need to be connected in a 21/2 Element WYE fashion. As shown in Figure 8, the CH1 or A phase connection is the black wire, the CH3 or C phase connection is the blue wire and the CH4 (optional channel) is the yellow wire.
NOTE: The CH2 (B) voltage is not connected in the 21/2 Element WYE system. The current channels are connected respectively with the voltage channel connections as shown in Figure 8. In order to monitor with the 21/2 Element WYE connected circuit type, the recorder must be initialized to 21/2 Element WYE.
2 Wire Single-phase
There are 3 connections associated with the 2 Wire Single-phase System including the current channel. CH1 voltage and current, and all the other channels are optional. Since the 2 Wire Single-phase System has no neutral connection, the white wire connection on the recorder needs to be made at the corresponding phase measurement. As shown in Figure 9, the white wire is connected to the common point and is all that is required to make up this connection.
Figure 9. 2 Wire Single-phase
The line connections are the remaining points that need to be connected in a 2 Wire Single-phase fashion. As shown in Figure 9, the CH1 connection is the black wire and is all that is required to make up the line connection. The CH1 current is connected respectively with the voltage channel connection as shown in Figure 9. In order to monitor with the 2 Wire Single-phase connected circuit type, the recorder must be initialized to WYE.
3 Wire Single-phase
There are 5 connections associated with the 3 Wire Single-phase System including the current channels. CH1 voltage and current, CH2 voltage and current and all other channels are optional. Since the 3 Wire Single-phase System has a neutral connection, the white wire neutral connection on the recorder needs to be made at this point. As shown in Figure 10, the white wire is connected to the common point and is all that is required to make up this connection.
Figure 10. 3 Wire Single-phase
The line connections are the remaining points that need to be connected in a 3 Wire Single-phase fashion. As shown in Figure 10, the CH1 connection is the black wire, the CH2 connection is the red wire. The current channels are connected respectively with the Voltage channel connections as shown in Figure 10. In order to monitor with the 3 Wire Single-phase circuit type, the recorder must be initialized to WYE.
Setting The Circuit Type
In order for the calculations to be correct when monitoring a specific circuit, the recorder must be initialized to monitor that circuit type. The circuit type is set on the Basic Initialization Screen as shown in Figure 11.
Figure 11. Circuit type selection
Conclusion
PMI offers the ability to monitor any circuit type found in the industry. With a little background knowledge in the circuit types that are commonly used in power quality monitoring scenarios, connecting your recorder will be easier and more reliable. The time spent reviewing the connection diagrams will be well worth the effort when investigating a power quality issue.
For a PDF of the recorder hookup diagrams visit the PMI website here.
D.J. Diehl
Design Engineer
ddiehl@powermonitors.com
https://www.powermonitors.com
(800) 296-4120
Power Monitors Inc.
800.296.4120
TheEngineers@powermonitors.com
http://www.powermonitors.com
