Mosa RENTAL GE 50 KR-5, Руководство по эксплуатации и обслуживанию

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6. Operation
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For cos ϕ values lower than 0.8, the alternator must be downgraded, because, at the same apparent power,
the alternator should provide a greater reactive power.
For the reduction coefficients, contact the Technical Support Service.
Asynchronous motor start
Starting an asynchronous motor by a generating set can be critical, due to the high starting currents that the
asynchronous motor requires (Iavv. = up to 8 times rated current In.).
The starting current must not exceed the overload current allowed by the alternator for short periods, gener-
ally 250-300% for 10-15 seconds.
To avoid oversizing the group, we recommend adopting some precautions:
•
When starting multiple motors, divide them into groups and arrange for them to start at intervals of 30-60
seconds.
• If the machine coupled to the motor allows it, set it for a reduced-voltage start, star/triangle start or with
autotransformer, or use a soft-start system.
In all cases, when the user circuit provides for the start of an asynchronous motor, it is necessary to check
that there are no utilities inserted in the system that, due to the transient voltage drop, may cause more or
less serious disruptions (opening of contactors, temporary power failure to command and control systems,
etc.).
Single-phase loads
The supply of single-phase utilities through three-phase generators requires some operational limitations.
• In single-phase operation, the declared voltage accuracy can no longer be maintained by the AVR elec-
tronic regulator, as the system becomes highly unbalanced.
The voltage variation is limited by the particular three-phase sensing AVR regulator, which tends to bal-
ance the three phase voltages.
When connecting multiple single-phase utilities, it is mandatory to distribute the utilities over the three
phases, in order to balance the system as much as possible.
• The maximum withdrawable power between Neutral and Phase (star connection) is generally 33% of the
rated three-phase power, or 40% if only one utility is connected on a single phase.