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Why The Electric Motor Cannot Start of Volvo Diesel Generator

Dec. 29, 2021

Today we will give you a brief introduction about the problem of the motor can not start in Volvo diesel generators.


The motor does not turn and there is no sound. The reason is that the motor power supply or winding has two-phase or three-phase open circuit. First check whether there is a power supply voltage. If there is no voltage in the three phases, the fault is in the circuit; if the three-phase voltage is balanced, the fault is in the motor itself. At this time, the resistance of the three-phase windings of the motor can be measured to find out the windings of the open phase.


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The motor does not turn, but there is a "buzzing" noise. Measure the motor terminal, if the three-phase voltage is balanced and rated, it can be judged as a serious overload. The inspection procedure is to remove the load first. If the motor speed and sound are normal, it can be determined that the load is overloaded or the mechanical part of the load is faulty. If it still does not turn, you can turn the motor shaft with your hand. If it is tight or unable to turn, measure the three-phase current. Lack of oil, bearing rust or severe damage, end cover or oil cover is installed too obliquely, rotor and inner bore collide (also called sweeping bore). If it is difficult to turn the motor shaft to a certain angle by hand, or if you hear a periodic "chatter" sound, it can be judged as sweeping. The reasons are: (1) The gap between the inner and outer rings of the bearing is too large, and the bearing needs to be replaced; (2) The bearing chamber (bearing hole) is too large, and the inner hole diameter is too large due to long-term wear. The emergency measures are electroplating a layer of metal or adding a sleeve, or you can punch some small points on the inner wall of the bearing; (3) The shaft is bent and the end cover is worn.


The Volvo generating set motor rotates slowly and is accompanied by a "humming" sound, and the shaft vibrates. If the measured current of one phase is zero and the current of the other two phases greatly exceeds the rated current, it means that it is two-phase operation. The reason is that the circuit or power supply is open in one phase or the motor winding is open in one phase.


When one phase of the small motor is disconnected, it can be checked with a megohmmeter, a multimeter or a school lamp. When inspecting a motor with star or delta connection, the joints of the three-phase windings must be disassembled to measure whether each phase is open. The windings of medium-capacity motors mostly use multiple wires and are connected in parallel around multiple branches. It is more complicated to check if several wires are broken or one parallel branch is disconnected. The three-phase current balance method and the resistance method are often used. Generally, when the difference of the three-phase current (or resistance) value is more than 5%, the phase with the small current (or the large resistance) is the open circuit phase. Practice has proved that motor open circuit faults mostly occur at winding ends, joints or lead wires.


Starlight Power was founded in 1974 and is one of the earliest manufacturers of generators and diesel generator sets in China. If you want get more information, please feel free to send email to sales@dieselgeneratortech.com we will pay highly attention on your question.

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