Leeson 174475, Инструкция по установке и эксплуатации

Страница: 56 / 80

18
BASE
(BASE FREQUENCY)
The BASE FREQUENCY determine the V/Hz ratio by setting the frequency at which the drive will out-
put full voltage to the motor. For most applications the base frequency should be set to match the motor's
rated frequency.
For example, if the drive is rated for 460 VAC output, and the BASE FREQUENCY is set to 60 Hz, the
drive will maintain a constant ratio of 7.66 V/Hz (except when AC BOOST or FX BOOST are active, see
Parameters 19 and 20) from 0 Hz to 60 Hz. This range is the region of constant torque. If the motor speed
is increased past 60 Hz, the output voltage remains constant while the frequency increases, resulting in a
reduced V/Hz ratio. This range, from 60 Hz to about 90 Hz, is the region of constant horsepower. Above
90 Hz, horsepower begins to drop off as frequency increases. Refer to Section 6.1 - DESCRIPTION OF
AC MOTOR OPERATION.
19
FX BOOST
(FIXED BOOST)
This parameter is used in applications which require high starting torque. FX BOOST increases the output
voltage at lower output frequencies (below 30 Hz for 60 Hz base frequency), in order to boost the torque
capability of the motor. Refer to the diagram below. The factory default for FX BOOST depends on the
horsepower rating. Refer to the table below:
54
FX BOOST FACTORY DEFAULT SETTINGS
HP
FACTORY
HP
FACTORY
DEFAULT DEFAULT
0.25 - 1 5.30% 15 2.20%
1.5 - 2 4.40% 20 2.00%
3 3.60% 25 1.80%
5 3.00% 30 1.60%
7.5 2.70% 40 1.20%
10 2.40% 50 - 60 0.80%