IMO HD2 IP Series, Инструкция по эксплуатации

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HD2 IP55 High-ingress Protection Series Inverter
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7.7.3 Failure to stop and indicator shimmering due to motor cable coupling
Interference phenomenon:
1. Failure to stop
In an inverter system where an S terminal is used to control the start and stop, the motor cable
and control cable are arranged in the same cable tray. After the system is started properly, the
S terminal cannot be used to stop the inverter.
2. Indicator shimmering
After an inverter is started, the relay indicator, power distribution box indicator, PLC indicator,
and indication buzzer shimmers, blinks, or emits unusual sounds unexpectedly.
Solution:
1. Check and ensure that the exception signal cable is arranged 20 cm or farther away from the
motor cable.
2. Add a safety capacitor of 0.1 μF between the digital input terminal (S) and the COM terminal.
3. Connect the digital input terminal (S) that controls the start and stop to other idle digital input
terminals in parallel. For example, if S1 is used to control the start and stop and S4 is idle,
you can try to connect connect S1 to S4 in parallel.
Note: If the controller (such as PLC) in the system controls more than 5 inverters at the same
time through digital input terminals (S), this scheme is not available.
7.7.4 Leakage current and interference on RCD
inverters output high-frequency PWM voltage to drive motors. In this process, the distributed
capacitance between the internal IGBT of a inverter and the heat sink and that between the
stator and rotor of a motor may inevitably cause the inverter to generate high-frequency leakage
current to the ground. A residual current operated protective device (RCD) is used to detect the
power-frequency leakage current when a grounding fault occurs on a circuit. The application of
a inverter may cause misoperation of a RCD.
1. Rules for selecting RCDs
(1) inverter systems are special. In these systems, it is required that the rated residual current
of common RCDs at all levels is larger than 200 mA, and the inverters are grounded reliably.
(2) For RCDs, the time limit of an action needs to be longer than that of a next action, and the
time difference between two actions need to be longer than 20 ms. For example, 1s, 0.5s,
and 0.2s.
(3) For circuits in inverter systems, electromagnetic RCDs are recommended. Electromagnetic
RCDs have strong anti-interference capability, and thus can prevent the impact of high-
frequency leakage current.
Electronic RCD Electromagnetic RCD
Low cost, high sensitivity, small in volume,
susceptible to voltage fluctuation of the grid
and ambient temperature, weak anti-
interference capability
Requiring highly sensitive, accurate, and
stable zero-phase sequence current
transformer, using permalloy high-permeability
materials, complex process, high cost, not
susceptible to voltage fluctuation of the power
supply and ambient temperature, strong anti-
interference capability