Specifications

182
Transducers
3-phase balanced circuit
When loads Z
.
a, Z
.
b and Z
.
c that are connected to a 3-
phase power supply are all equal, the respective voltages
V
.
RS, V
.
ST and V
.
TR are all equal in magnitude and phase
difference among the respective voltages. The respective
line currents I
.
R, I
.
S and I
.
T are also all equal in magnitude
and phase difference. Such a circuit is called a 3-phase
balanced circuit.
Burnout
A term often used with temperature transducers and refers
to a function by which, when an input line into the
temperature transducer or a temperature sensor beyond
the input line, becomes disconnected, the output is rises
above the effective output range (normally, the output is
increased ... positive burnout).
Cold junction compensator
A thermocouple sensor’s electromotive force is input to a
thermocouple temperature transducer. The voltage
corresponds to a temperature less than T°C, the
temperature measured at the point only affected by the
ambient temperature, Ta°C, thereby compensating for the
Ta°C part. This action is performed by a cold junction
compensator, which is either attached externally to the
transducer or built-in.
Zero adjuster
With a zero adjuster, the output range is increased or
decreased by a fixed value (approximately ±0.3~±5% with
respect to the span) as shown in the figure below.
Span adjuster
With a span adjuster, the output increases or decreases at
the same proportion (±3%~±15% with respect to the rated
output) with zero input as the base point.
3-phase unbalanced loads
When loads Z
.
a, Z
.
b and Z
.
c that are connected to a 3-
phase power supply are not equal, the respective line
currents I
.
R, I
.
S and I
.
T are also not equal in magnitude and
phase difference among the respective currents. Such
loads are called 3-phase unbalanced loads.
Among phase angle transducers, there are those that can
be used with 3-phase unbalanced loads (for 3-phase
unbalanced loads) and those that cannot be used with 3-
phase unbalanced loads (for 3-phase balanced circuit).
Third harmonic
A voltage or a current with frequency that is 3 times that of
the fundamental frequency voltage or current
(fundamental wave: a 60Hz AC voltage or current in the
case of an input frequency of 60Hz).
When a third harmonic or other harmonic is contained, the
waveform becomes distorted and becomes a cause of
measurement error.
IR
Zc
Za
IT
IS
VST
VTR
VRS
Zb
Power supply side
Fundamental
wave
Third harmonic
Synthesized waveform
(waveform resulting from synthesis of the
fundamental wave and the third harmonic
shown above)
Zero adjustment
Output
Input
Span adjustment
Output
Input