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“B” Group: Fine Tuning Functions
Configuring
Drive Parameters
3–30
B_88: Restart Mode Configuration – You can configure how the inverter resumes
motor output control after a free-run stop. Setting B_88 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. However, applications such
as HVAC fan control will often use a free-run stop. This practice decreases dynamic
stress on system components, prolonging system life. In this case, you will typically set
B_88=01 in order to resume from the current speed after a free-run stop (see diagram
below, right). Note that using the default setting, B_88=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 3–22), 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.
An additional parameter further configures all instances of a free-run stop. Parameter
B_03, Retry Wait Time Before Motor Restart, sets the minimum time the inverter will
free-run. For example, if B_03 = 4 seconds 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.
B_86 Frequency scaling
conversion factor
Specify a constant to scale the
displayed frequency for D_07
monitor, range is 0.1 to 99.9
✘ 1.0 1.0 1.0 —
/Hz01.0 0.00
B_87 STOP key enable Select whether the STOP key
on the keypad is enabled, two
option codes:
00 ...enabled
01 ...disabled
✘ 00 00 00 —
STOP-SW ON
“B” Function
Run
Mode
Edit
Defaults
Func.
Code
Name /
SRW Display
Description
–FE
(CE)
–FU
(UL)
–FR
(Jpn)
Units
B_88
=
00 B_88
=
01
[FW, RV]
Motor
speed
t
Resume from 0Hz
Zero-frequency start
t
Resume from current speed
[FW, RV]
Motor
speed
B03
Wait time
[FRS]
[FRS]