Function Of Parameter - Toshiba TOSVERT VF-A7 Function Manual

4. Function of parameter

When the inverter is used in combination with the mechanical brake of a lifting machine (crane, hoist,
etc.), the load fall by torque reduction can be prevented by carrying out the shortest acceleration of the
mechanical brake operation delay time.
Moreover, this parameter raises response in inching operation in order to control the load not to slip
down.
= 0 mode (standard)
Frequency [Hz]
When torque limit is
not activated
Torque [N⋅m]
Torque limit
level
Mechanical
ON
brake
= 1 mode (without speed cooperation)
Frequency [Hz]
Operation frequency
Torque [N⋅m]
Torque limit
level
Mechanical
ON
brake
Operation frequency
Actual speed
OFF
(Released)
Actual speed
(Acceleration rate is determined
by torque limit.)
Torque limit is sustained after
the mechanical brake is
released.
OFF
(Released)
- 3 -
Operation frequency is controlled
when torque limit is activated.
Therefore, actual speed is
Time [s] controlled to follow the operation
frequency always.
Since the operation frequency is
raised after torque declines with
release of the mechanical brake,
the time that the actual speed
corresponds to the operation
frequency is time lag in
Time [s] mechanical brake operation +
acceleration time.
Time [s]
Operation frequency becomes
high ahead of torque limit even
when it is activated.
When torque declines with release
of the mechanical brake, it is
sustained at the limit level and
actual speed is controlled to follow
the operation frequency.
This mode functions not only to
prevent the load from falling but to
raise response in inching
operation.
Time [s]
Time [s]
Time [s]
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