Fuji Electric FRENIC-AQUA series, User Manual

Page: 742 / 751

App. A Advantageous Use of Inverters (Notes on electrical noise)
A-9
App.
Table A.2 Continued
No.
Target
device
Phenomena Noise prevention measures
Notes
1) Connect the ground
terminals of the motors in
a common connection.
Return to the inverter
panel, and insert a 1
μ
F
capacitor between the
input terminal of the
inverter and ground.
1) The effect of the
inductive filter
and LC filter may
not be expected
because of sound
frequency
component.
2) In the case of a
V-connection
power supply
transformer in a
200V system, it is
necessary to
connect
capacitors as
shown in the
following figure,
because of
different
potentials to
ground.
3 Tele-
phone
(in a
common
private
residence
at a
distance
of 40 m)
When driving a ventilation
fan with an inverter, noise
enters a telephone in a private
residence at a distance of
40m.
<Possible cause>
A high-frequency leakage
current from the inverter and
motor flowed to grounded
part of the telephone cable
shield. During the current's
return trip, it flowed through
a grounded pole transformer,
and noise entered the
telephone by electrostatic
induction.
4 Photo-
electric
relay
A photoelectric relay
malfunctioned when the
inverter runs the motor.
[The inverter and motor are
installed in the same place
(for overhead traveling)]
<Possible cause>
It is considered that induction
noise entered the
photoelectric relay since the
inverter's input power supply
line and the photoelectric
relay's wiring are in parallel
separated by approximately
25 mm over a distance of 30
to 40 m. Due to conditions of
the installation, these lines
cannot be separated.
1) As a temporary measure,
Insert a 0.1
μ
F capacitor
between the 0 V terminal
of the power supply
circuit in the detection
unit of the overhead
photoelectric relay and a
frame of the overhead
panel.
2) As a permanent measure,
move the 24 V power
supply from the ground to
the overhead unit so that
signals are sent to the
ground side with relay
contacts in the ceiling part.
1) The wiring is
separated by more
than 30 cm.
2) When separation
is impossible,
signals can be
received and sent
with dry contacts
etc.
3) Do not wire
low-current signal
lines and power
lines in parallel.