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6
Verify that the product's transmit signal level is within acceptable limits. This
is done by deliberately loading the isolated power mains on which the product
under test is operating and comparing the output transmission level under load
against a reference level.
7
Verify that the product's receive sensitivity is within acceptable limits. This is
performed using a pair of PLCA-22 analyzers. The communication signal level
of the transmitting PLCA-22 analyzer is gradually decreased and the receive
performance of the product under test is monitored and compared against
reference performance levels.
Power Line Test Isolator
The circuit shown in figure 7.1 is used to create a power mains environment that is
isolated from the noise and loading present on typical power mains. When properly
constructed, the circuit provides 60 to 80dB of isolation between the power mains
and the product under test at the PLT-22 transceiver’s communication frequencies.
The effectiveness of the circuit should be verified by using a pair of PLCA-22
analyzers communicating between the power mains input and the output. To
perform this verification, set the PLCA-22 analyzer that is connected to the input
side of the isolator to send packets at 3.5Vpp in UnackPri mode in the C band. The
green bargraph meter on the receiving analyzer (connected to the “product under
test” output) should indicate a signal strength no higher than –60dB. Without any
packet transmission, no LEDs above the –78dB primary and secondary signal
strength LEDs should be illuminated or flashing. Note that Neon power indicators
should not be used on the isolated output, since they frequently produce noise in the
–72dB range.
Since the isolator does not completely block communications from other PLT-22
transceivers communicating on the power mains, receive testing must only be
performed when there is no other packet activity on the power mains.
All capacitors 0.47µF 250VAC (X2 type)
All resistors 20ž 1 Watt ±5%, unless otherwise indicated
Isolation transformer rating based on load requirements
Line in
Neutral in
Earth
Line out
Neutral out
Earth
From power
mains
To product
under test
R
C
R
R
C
C
C
C
C
50 ž
±5%, 1/4W
C
Figure 7.1
Power Mains Isolation Circuit
L
ON
W
ORKS
PLT-22 Transceiver User’s Guide
7-3
Содержание LONWORKS PLT-22
Страница 6: ...iv Echelon...
Страница 14: ...1 8 Introduction...
Страница 67: ...LONWORKS PLT 22 Transceiver s User Guide 5 7 Figure 5 3 Capacitor Input Power Supply Schematic...
Страница 92: ...6 10 Design and Test for Electromagnetic Compatibility...
Страница 110: ...7 18 Communication Performance Verification...
Страница 114: ...8 4 References...
Страница 118: ...A 4 Appendix A...