YOKOGAWA CENTUM CS, Technical Information

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1. System Installation Requirements
1-14
TI 33J01J10-01EN
The system operating voltage range is shown below based on the relationship between effective
and peak values at the power input terminal of each system. Apply AC power within these ranges
to operate the system.
TIP
Average rectified measuring meters such as testers cannot measure effective values accurately. Use Yokogawa’s
WT series power meter or an meter, which enables effective values, peak values, and waveform distortion to be
measured with one unit.
120
125 127
90
100
110
120
132
130 140 150 160 170
187
Peak value (V op)
V
V
Effective
value
(V rms)
Effective
value
(V rms)
System operating
voltage range
F010302.ai
274
200
198
220
240
264
280 310 340 370
374
Peak value (V op)
V
V
180
System operating
voltage range
V op= 2 V rms V op= 2 V rms
Figure System Operating Voltage Range
The DC stabilized power supply used by Field Control Unit of the CENTUM VP uses a compact
and efficient switching regulator circuit. In this circuit, output voltage cannot be maintained if the
energy (terminal potential) of the smoothing capacitor falls below a predetermined value. The
circuit monitors the capacitor terminal voltage and regards it as power failure if the voltage falls in
the danger zone, causing the system to enter power fail mode (non-detected momentary power
failure: up to 20 ms).
Current flows to the capacitor in this circuit when AC input voltage is higher than the capacitor
terminal voltage. Since the capacitor is charged by the peak value of the input waveform, it is
required that both the effective voltage value and the peak value conform to specifications.
F010303.ai
Rectification, smoothing,
power factor correction
Input voltage
monitoring
DC/AC Rectification
Output voltage
monitoring
PWM
ACRDY
DCRDY
Input
(AC)
Power/failure
control
Output
(DC)
System
control
signal
(Waveform
monitoring)
Insulation
Smoothing capacitor
terminal voltage
Figure FCU Power Circuit Diagram
Dec. 28, 2015-00