Hitachi L200 Manual Do Utilizador

Página de 280
“B” Group: Fine Tuning Functions
Configur
ing
Dr
iv
e P
a
ra
m
e
ters
3–40
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 matching). 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 below, right). 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 
terminal [FRS] signal. If all free-run stop behavior is important to your application (such 
as HVAC), be sure to configure each event accordingly.
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.
Stop Mode = free-run stop
B091 = 01
B091 = 01
B088 = 00
B088 = 01
[FW, RV]
Motor 
speed
t
Resume from 0Hz
Zero-frequency start
t
Stop Mode = free-run stop
Resume from current speed
[FW, RV]
Motor 
speed
Wait time
B003