Application Guide - NP900 Series
258 (504
)
A996A
Figure 3.3.3-126 Motor starting is too long.
Reasons for too long starting may be in the drive and application as well as in the feeding
network if started motor is very large and the feeding network is weak the voltage may
drop so that the motor cannot provide needed torque for normal starting and the start-up
situation is prolonged. For this reason the I
2
t mode is suggested since it will compensate
the voltage drop in taking to account the lower voltage caused lower starting current. If
definite time is preferred for the LRC function it may be so that the starting is well in action
but the user allowed time is spent due to low network voltage caused lower current and
lower torque the function may trip before the starting is over even the motor is not
stressed yet too much and could still continue the starting.
If in the application is available so called speed switch which activates when the motor
shaft is rotating / accelerating it can be used to prolong the allowed starting of the motor to
longer than the set maximum starting duration. If the speed switch is used and similar
situation happens that the motor is starting longer than it should the speed switch is noting
that the startup of the motor is still going ok and LRC function lets the starting situation
continue.
Содержание NP900 Series
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Страница 49: ...Application Guide NP900 Series 49 504 A996A Figure 3 2 1 3 25 Definite time operating characteristics...
Страница 50: ...Application Guide NP900 Series 50 504 A996A Figure 3 2 1 3 26 IEC predefined characteristics NI VI LTI and EI...
Страница 52: ...Application Guide NP900 Series 52 504 A996A Figure 3 2 1 3 28 IEEE predefined characteristics EI MI and VI...
Страница 243: ...Application Guide NP900 Series 243 504 A996A Figure 3 3 2 1 122 NPS biased thermal trip curves with kNPS values 7 and 10...
Страница 491: ...Application Guide NP900 Series 491 504 A996A 3 7 5 6 SETTING EXAMPLE...
Страница 504: ...Application Guide NP900 Series 504 504 A996A A996A...