Fuji Electric FRENIC-HVAC User Manual page 51

Symbol Name
- Since low level analog signals are handled, these signals are especially susceptible
to the external noise effects. Route the wiring as short as possible (within 20 m (66
ft)) and use shielded wires. In principle, ground the shielded sheath of wires; if
effects of external inductive noises are considerable, connection to terminal [11]
may be effective. As shown in Figure 2.2, be sure to ground the single end of the
shield to enhance the shield effect.
- Use a twin-contact relay for low level signals if the relay is used in the control
circuit. Do not connect the relay's contact to terminal [11].
- When the inverter is connected to an external device outputting the analog signal,
the external device may malfunction due to electric noise generated by the inverter.
If this happens, according to the circumstances, connect a ferrite core (a toroidal
core or equivalent) to the device outputting the analog signal or connect a capacitor
having the good cut-off characteristics for high frequency between control signal
wires as shown in Figure 2.3.
- Do not apply a voltage of +7.5 VDC or higher to terminal [C1]. Doing so could
damage the internal control circuit.
Figure 2.2 Connection of Shielded Wire
Functions
Figure 2.3 Example of Electric Noise Reduction
2-18
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