Hitachi X200 Series instruction manual 42, Frs

3−42

B091/B088: Stop Mode / Restart Mode Configuration – 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 called frequency pull-in). 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: frequency pull-in 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.

Configuring Drive Parameters

An additional parameter further configures all instances of a free-run stop. Parameter B003, Retry Wait Time Before Motor Restart, sets the minimum time the inverter will free-run. For example, if B003 = 4 seconds (and B091=01) and the cause of the free-run stop lasts 10 seconds, the inverter will free- run (coast) for a total of 14 seconds before driving the motor again.

Further explanation of the Frequency pull- in resume: In the figure below: Frequency pull-in resume, after waiting time set in B003, inverter tries to catch the speed and outputs the speed set in B011. At this moment, if the motor current rises up to the value set in B030, the inverter decreases the speed according to the deceleration time set in B029, and finally comes to the required speed. Following are the related parameters for this control.

Code Parameter contents

B011	Start freq to be used in case of freq
	matching restart
B029	Deceleration rate of frequency matching
	restart setting
B030	Current level of frequency matching
	restart setting
B088	Restart mode after FRS
B091	Stop mode selection

Zero frequency resume

B091 = 01 Stop mode = free-run stop

B088	= 00	Resume from 0Hz
[FRS]
	0	t
Motor		Zero-frequency start
speed
	0	t

Frequency pull-in resume

B091 = 01	Stop mode = free-run stop
	Resume from current speed
B088 = 01

[FRS]
0		t
Wait time	B011	B029
B003
Motor
speed
0		t
Motor	B030
current
RMS		t
0