Stop Mode / Restart Mode Configuration - Hitachi WJ200 Series Instruction Manual

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Stop Mode / Restart Mode Configuration: B091/B088 – You can configure how the
inverter performs a standard stop (each time Run FWD and REV signals turn OFF).
Setting B091 determines whether the inverter will control the deceleration, or whether
it will perform a free-run stop (coast to a stop). When using the free-run stop selection,
it is imperative to also configure how you want the inverter to resume control of motor
speed. Setting B088 determines whether the inverter will ensure the motor always
resumes at 0 Hz, or whether the motor resumes from its current coasting speed (also
active frequency matching
called ). The run command may turn OFF briefly, allowing
the motor to coast to a slower speed from which normal operation can resume.
In most applications a controlled deceleration is desirable, corresponding to B091=00.
However, applications such as HVAC fan control will often use a free-run stop (B091=01).
This practice decreases dynamic stress on system components, prolonging system life.
In this case, you will typically set B088=01 in order to resume from the current speed
after a free-run stop (see diagram down below: active frequency matching resume). Note
that using the default setting, B088=00, can cause trip events when the inverter
attempts to force the load quickly to zero speed.
NOTE: Other events can cause (or be configured to cause) a free-run stop, such as power
loss (see "Automatic Restart Mode" on page 3-32), or an intelligent input terminal [FRS]
signal. If all free-run stop behavior is important to your application (such as HVAC), be
sure to configure each event accordingly.