or the temperature value measured may be false. A connection wire’s maximum cross section area is 2
.
5
mm
2
in case of all screw terminals.
The SMC 144 is primarily intended for DIN-rail mounting. Dimensions of the instrument are on figure 6.
There are also positions marked with dash dot lines of holes for wall-mounting with three screws.
60.6
90
21.5
10
45
62
58
106
99.8
30.3
SMC 144
Power Analyzer
00
1
08
20
12
P0
50
Figure 6: Rozmˇ
ery pˇ
r´ıstroje SMC 144.
2.3.1
Voltage
The instrument’s power supply voltage (see chapter 4) must be connected to the terminals X1 and X2 via
a circuit breaking device (power switch – see installation wiring diagram on figure 7). It has to be located
left to the instrument within an easy reach by the operator. The circuit breaking device must be identified as
the equipment power disconnection switch. A circuit breaker of the nominal value 1
A
is a convenient circuit
breaking device, its function and position however have to be clearly identified (using the ‘0’ and ‘I’ symbols,
respectively, in accordance with IEC EN 61010-1). Internal power supply is galvanically isolated from internal
circuits.
The measured voltages are connected to the terminals L1, L2, L3, L4, the common terminal to connect
the neutral wire to being identified as N. It is suitable to protect the measured voltage lines for example with
1
A
fuse links. The measured voltages can also be connected via a metering voltage transformers. All voltage
measurement inputs are connected with internal circuits over high impedances.
2.3.2
Current
For proper current measuring, external through-hole or clamp-on current sensors must be installed with correct
polarity. Figure 7 ilustrates proper connection polarity of precision through-hole current transformers. Intended
direction of power flow is from left (source) to right (load). It is highly recommended to verify correct wiring
and polarity of currents with phasor diagram in actual data using software ENVIS.Daq.
The current inputs are directly connected with internal cirtuits. Inputs
l1
,
l2
,
l3
and
l4
are internally
connected together. Inputs
l
i
and
k
i
are connected through shunt resistors. Please note, that CURRENT
INPUTS CAN NEVER BE USED FOR DIRECT MEASUREMENT! Always use only recommended supplied
current transformers with low-mA output.
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