ABB ACS800-67, Описание системы и руководство по запуску

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Practical examples 79
Stator current and voltage measurement

NUIM-6x voltage measurement
Voltages U1,V1 and W1 are measured at both sides of the stator circuit
breaker/contactor(s). The 690 V AC grid voltage is connected to the Voltage and Current
Measurement unit (NUIM).
Stator flux is measured through a low pass filter which has different time constants for
690 V AC and 575 V AC. The control program must know which one is in use. The used
voltage is defined as follows:

NUIM-1x voltage measurement
If voltage measurement is accomplished using an instrument voltage transformer the
measurement board used is of the type NUIM-10C. In this case the maximum measurable
flux must be calculated by the formula:
•
Un 1 = voltage transformer primary side voltage in volts (V)
•
Un 2 = voltage transformer secondary side voltage in volts (V)
•
f = grid frequency in hertz (Hz)
For more information on the NUIM Voltage and Current Measurement unit, see the
converter hardware manual.

NUIM-1x and NUIM-6x current measurements
Two stator currents are measured from phases U1 and W1 through current transformers
(CT). The CT ratio is the ratio of primary current input to secondary current output at full
load. For example a CT with a ratio of 2500:1 is rated for 2500 primary amperes at full load
and will produce 1 A of secondary current when 2500 A flow through the primary. If the
primary current changes the secondary current output will change accordingly. For
example if 1500 A flow through the 2500 A rated primary the secondary current output will
be 0.6 A (1500 : 2500 = 0.6 : 1). An example diagram of the current measurement is
Parameter Setting
For 690 V / 50 Hz 99.27 MAX MEAS FLUX < 2.43936 Wb
99.33 NUIM61 PHS OFFSET < 47.06 deg
For 575 V / 60 Hz 99.27 MAX MEAS FLUX < 1.605 Wb
99.33 NUIM61 PHS OFFSET < 44.35 deg
For 690 V / 60 Hz 99.27 MAX MEAS FLUX < 2.407 Wb
99.33 NUIM61 PHS OFFSET < 44.35 deg
99.27 MAX MEAS FLUX
Un 1
Un 2
-----------
5.963541 1 f 0.065175
× ( )
+
⋅
f
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2
⋅
=