Fairford Electronics QFE Series, Руководство пользователя

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QFE
page 3-23
Applications
FD841405_F
Appendix A: Glossary of Terms
Breakaway Torque The minimum torque required to achieve rotor movement for the motor with its
load.
Current Limit The current at which the ramp is held. For the QFE, current limit is only active
during start-up where it contributes to the motor control function. This feature
is particularly useful when starting high-inertia loads that require an extended
start-up period. (See also Overload Level.)
Direct-On-Line (DOL) The direct connection and disconnection of a motor from the AC mains supply
by means of a contactor or switch. Acceleration and operation is at full mains
voltage only.
Inrush Current or Locked Rotor Current
The current that flows at the instant of connection of a motor to the power
source. It is limited by the impedance presented by a de-energised motor and
the applied voltage. Usually expressed as a multiple of motor full-load current.
Kick-start Kick-start voltage is the percentage of supply voltage applied before
commencing ramp-up when a load has a high breakaway torque and the
standard settings of pedestal voltage may not allow sufficient torque to be
developed by the motor to cause acceleration.
Overload Level The level of current at which the controller overload begins to integrate. For
the QFE, the overload detector is always active and provides protection against
prolonged over-current operation.
Pedestal Voltage The voltage that the unit applies to the motor at start-up. It is expressed as a
percentage of the rated supply voltage.
Power Factor The ratio, expressed as a trigonometric cosine, of the real power consumption
to the apparent power consumption.
Top of Ramp (TOR) The unit achieves Top of Ramp (TOR) when it completes the start-up stage of
motor control. This occurs when the voltage applied to the motor first equals
the mains supply voltage.)
Soft-start Soft-start is the regulation by electronic means, of the supply voltage from an
initial low value to full voltage during the starting process. This over-comes the
inherent drawbacks of a switched supply. The motor torque is modified in
proportion to the square of the voltage applied.
Trip A trip occurs when the unit removes power to the motor because its operation
equals the limit imposed by one of its self-protection features.