Which Things Do You Need to Consider When Purchasing Standby Generator?

by Starlight Generator dieselgeneratortech

As an emergency backup power source, diesel generator sets are increasingly accepted and used by many industries due to its reliability, timeliness and safety. However, purchasing a suitable standby generator is not an easy task.

If you decide to buy a diesel generator set, you are advised to read the below instructions before placing an order.

1. Common Enquiry

A. Power supply parameters: output voltage 230V/400V, frequency 50HZ, genset speed 1500r/min.

B. Automatic display and recording of operating data: including water temperature, oil pressure, speed and running hours.

C. Protection device: diesel engine overspeed, start or stop failure, low oil pressure, high oil temperature, excessive cooling water temperature, generator overload, short circuit, loss of pressure and failure of the vehicle, etc, the genset will give alarm according to different conditions (including lighting, audible alarm), open and even stop automatically.

D. It should be equipped with 24V DC starter motor and battery as electric starting system battery power is monitored by computer control.

2. Capacity

A. The rated operating power of the generator set is not less than the rated power of the stable load.

B. The standby operation power of the generator set is not less than the peak power of the load.

C. When the maximum motor starts, the instantaneous voltage drop of the generator is no more than 15%-20%.

3. Selections of Starting Method

There are three ways to start a diesel engine: manual start, electric start and compressed air start. Among them, the electric starting is to use the electric motor as the power to drive the crankshaft to rotate through the transmission mechanism, so that the diesel engine is started, the power supply battery used by the electric motor, and the starting mode should be adopted in the high rise building. At the same time, the selected genset should be equipped with fast automatic start and automatic power switch device to ensure power supply within 15s after the power supply of the city network is interrupted.

4. Speed

The diesel engine used for power generation has an adjustment diesel engine with a speed of not less than 1000r/min, the medium speed diesel engine has two speeds of 750r/min and 600r/min. In the high rise building, an adjustment unit with a rotational speed of 1500r/min should be used. This unit has a large volume per unit volume, so the volume is small and the weight is light, which can save floor space. The disadvantages of large running parts and short life spans are not considered for emergency genset with short running times.

5. Does The Generator Set Have a Supercharger?

When the generator set is equipped with a supercharger, the air required for combustion is supercharged by the supercharger and sent to the diesel engine, so that the density of the intake air is greatly increased. The same cylinder volume can burn more fuel, and the same type of non-supercharging. After the diesel engine is boosted, its output power can be increased by 50%. the turbocharger of the general diesel engine is an exhaust gas turbocharger, and the exhaust gas discharged from the diesel engine drives its work. The main disadvantage of the supercharged diesel engine is that the supercharger has a high rotational speed, short life span, and is prone to failure. But currently, the new machine has solved these problem and make it better.

6. Excitation Mode Selection

There are many kinds of excitation devices, such as a generator with a DC exciter, a self-excited constant voltage generator without a DC exciter, and a brushless excitation generator. The brushless excitation generator is a new type of generator developed in recent years. This kind of generator completely eliminates various carbon brushes and it reliable in operation. When used with the automatic voltage regulating device, the static voltage adjustment rate error can be guaranteed within 2.5%. This type of machine can adapt to various operating modes, and it is easy to realize automatic or remote control of the genset.

7. Selection of Cooling Method

There are two types of cooling methods for diesel engines: water cooling and air cooling. The complete unit of closed water circulation cooling is widely used in high-rise buildings due to its small footprint.

8. Selection of Genset Automatic Power

As an emergency generator set, the genset can quickly supply power to the emergency load when the external power supply fails. Therefore, the generator set should have the single-machine automation functions such as emergency self-start, automatic shutdown, automatic fault protection and recording mentioned above. For the specific situation, the following automation functions are selected.

A. Automatic grading loading: Some units are not allowed to suddenly increase the full load, and also prevent the inductive load from starting at the same time. Automatic grading loading can be set.

B. Automatic parallel: When the unit is automatically connected, the automatic parallel system can be set to automatically parallel the vehicle in the same way.

C. Automatic frequency modulation and load regulation: When the machine is running in parallel, the unit throttle is automatically adjusted to keep the power supply frequency and the load of each unit within the allowable deviation range.

D. Remote control of the unit: The genset needs to have RS232 standard interface and communication protocol, in line with the world-wide Lonworks technical standards.

E. Automatically maintain the starting state: The auxiliary system of the generator's starting, lubrication, fuel and cooling should be automatically kept ready to start, including automatic charging, automatic heating of lubricating oil and cooling water.