For manually quasi-synchronizing method ( the nonimal frequency is 50 Hz ), the allowable differences of voltage, frequency and primary phase angle is ( ).
A. △U≤±6%UN、△f≤±0.5Hz、△δ≤±30°
B. △U≤±10%UN、△f≤±0.5Hz、△δ≤±15°
C. △U≤±10%UN、△f≤±2Hz、△δ≤±30°
D. △U≤±10%UN、△f≤±2Hz、△δ≤±15°
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During parallel operation, unless the disassemble inspection is performed, otherwise we don’t have to check whether ( ) or not.
A. the voltage effective value is the same
B. frequency is the same
C. the phase angle is the same
D. the phase sequence is the same
When two synchronous generators parallel running,there must have ( ).
A. equal voltage/equal current/ equal frequency
B. equal voltage/ equal frequency
C. equal current/ equal frequency
D. equal active power/ equal reactive power
For essential loads onboard the ship, they are directly fed by main switchboard, so as to ( ).
A. Save money
B. easy operation
C. enhance the reliability of essential loads
D. improve the useage of essential loads
( ) are powered directly by the main switchboard.
A. deck machineries
B. low capacity load
C. some essential loads
D. stationary submersible pump
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