For example, 300KW Chongqing Cummins generator set high-rise building reserve fuel consumption rate curve change is relatively flat, low load is also economic (2), Cummins generator set is reliable and durable. Because there is no ignition system, low failure, (3), widely used (4), with low emissions (5), fire safety (6), start quickly, and can quickly reach full power (6), maintenance, simple operation, less people, easy maintenance during standby (7), the construction of the diesel generator set and generating low comprehensive cost of natural gas reserves, import diesel generator needs to be fixed gas source. And it must be used for a long time. In order to recover the early cost of gas units do not have the advantages of diesel generator sets. To sum up, if it is a standby generator set, it is recommended that diesel generator set, because the early investment is small, Cummins generator set technology is mature, imported diesel generator stability is high, small size, small footprint, light weight, fast emergency response, low cost, late maintenance is simple and convenient. If it is a long service cycle and has a high professional level, it is recommended to use gas, because the difference in the fuel cost of gas is the need to slowly accumulate the price difference to recover the early equipment. The above content is provided for the pioneering power. Theory of diesel generator set to the importance of the aquaculture industry, traditional breeding has gradually to the large-scale development, with the development of science and technology, aquaculture production process is especially important for the power supply problem, the following analysis for everyone: traditional farming scale at the same time, more need to increase the mechanization of operations, from the feed processing, the mechanization of farming equipment and ventilation cooling equipment is, import diesel generator and the use of mechanical equipment determines the aquaculture industry demand for electricity is not continuous. Cummins generator set a generating set when its running speed at 1500 RPM, a metres from the unit will produce 105 decibels of noise, to avoid the noise coming from machine room, sound engineering should include the following several parts: room to sound attenuation: every room has more than one entry, at least from the perspective of the sound room doors should not set too much, usually set a door, a door, as far as possible, not more than 3 square meters of area, structure in the framework of metal, internal attached high intensity sound insulation materials, external for the metal plate, mute door work closely with the up and down walls and doors. Diesel engine air intake system muffler: when the diesel engine is working, there must be enough air intake to maintain the normal operation of the unit. Generally, the air intake system should be set directly opposite the fan exhaust outlet of the unit. According to our experience, the air intake is forced and the air is pumped into the machine room by the blower through the muffler air groove. Diesel engine exhaust system noise: when the diesel engine adopts the water tank fan system for cooling. In addition to the normal supply of mains power, the configuration of diesel generator set as backup power supply should be considered. Is particularly important in the process of aquaculture is ventilation and cooling in the summer of high temperature weather was relatively closed aquaculture workshop temperature is higher, once the outage all mechanical equipment to stop working, the first will appear the high temperature and ventilation flow phenomenon, if there is no diesel generating set at this time to provide enough power for ventilation cooling equipment continue to work, breeding objects will appear because of the high temperature group die group of injury problems. As shown in the figure. The earthed object in the figure is a conductor buried in the ground and in direct contact with the ground. A. Working Grounding Power system is often grounded at the neutral point (see figure) for the needs of operation and safety. This kind of grounding is called working grounding. Working grounding has the following purposes :(1) to reduce the electric shock voltage. In an ungrounded neutral system, when one phase is grounded and the human body touches one of the other two phases, the shock voltage is 1.732 times the phase voltage. In a neutrally grounded system, the shock voltage is reduced to equal or close to the phase voltage. (2) quickly cut off the faulty equipment. In the system with neutral point not grounded, when one phase is connected to the ground, the grounding current is very small (because there is capacitance and insulation resistance between the wire and the ground, which can also form the current path) is not enough to make the protection device to operate and cut off the power supply. The grounding fault is not easy to be found, and will last for a long time, which is unsafe for personal safety. In the neutral grounding system, the grounding current after a phase is larger (close to single-phase short circuit) protection device quickly action.