GE PQMII, Инструкция по эксплуатации

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2–16 PQMII POWER QUALITY METER – INSTRUCTION MANUAL
CHAPTER 2: INSTALLATION
FIGURE 2–11: Analog Input Multiplexing
• Aux 1/2/3 Relay : When a switch input is assigned to an Auxiliary relay, a closure on
the switch input causes the programmed auxiliary relay to change state. This
selection is available only if the Control (C) option is installed.
• Clear Energy : When a switch input is assigned to “Clear Energy”, a closure on the
switch input will clear all Energy data within the PQMII.
• Clear Demand : When a switch input is assigned to “Clear Demand”, a closure on the
switch input will clear all Demand data within the PQMII.
2.2.9 Analog Outputs (Optional)
The PQMII has four current outputs when the transducer option is installed (T20 = 4 to 20
mA, T1 = 0 to 1 mA in the order code). These outputs can be multiplexed to produce 8
analog transducers. This output is a current source suitable for connection to a remote
meter, chart recorder, programmable controller, or computer load. Use the 4 to 20 mA
option with a programmable controller that has a 2 to 40 mA current input. If only a
voltage input is available, use a scaling resistor at the PLC terminals to scale the current to
the equivalent voltage. For example, install a 500
Ω resistor across the terminals of a 0 to
10 V input to make the 4 to 20 mA output correspond to 2 to 10 V (R = V/I = 10 V / 0.02 A =
500
Ω ). Current levels are not affected by the total lead and load resistance which must not
exceed 600 Ω for the 4 to 20 mA range and 2400 Ω for the 0 to 1 mA range. For readings
greater than full scale the output will saturate at 22 mA (4 to 20 mA) or 1.1 mA (0 to 1 mA).
These analog outputs are isolated and since all output terminals are floating, the
connection of the analog output to a process input will not introduce a ground loop. Part of
the system should be grounded for safety, typically at the programmable controller. For
floating loads (such as a meter), ground Terminal 24 externally.
The outputs for these transducers can be selected from any of the measured parameters
in the PQMII. The choice of output is selected in the
S2 SYSTEM SETUP ÖØ ANALOG OUTPUT 1(4)
setpoints group. See 5.3.2: Analog Outputs for a list of available parameters. Each analog
output can be assigned two parameters: a main parameter and an alternate parameter.
Under normal operating conditions, the main parameter will appear at the output
terminals. To select the alternate parameter, one of the switch inputs must be assigned to
“SELECT ANALOG OUT” and the switch input must be closed (assuming normally closed
activation). By opening and closing the switch input, two analog output parameters can be
multiplexed on one output. This effectively achieves 8 analog outputs for the PQMII.