Why not UPS Charge While on Generator Power

by Dieselgenerator Tech ***

The full name of UPS is Uninterruptible Power System. The structure of UPS power supply is composed of a set of AC, DC charging and AC / DC inverter devices. The battery in UPS is in the charging state when the mains supply is normal. Once the mains power is interrupted, the storage battery will immediately output the stored DC power to the inverter to supply the current to the computer equipment, so as to maintain the continuity of power supply to the computer equipment.


The generator can not directly charge the UPS. The main reason is that UPS power supply and the generator circuit are not synchronized. Once connected, it will cause a certain increase in the failure rate of the UPS power supply. However, it is not impossible to connect the generator under the operation of professional manufacturers. So you have to find professionals to operate for you.


UPS power supply and generator can be used at the same time, but short circuit must be prevented. Generally, it needs people who are professional in generator and UPS power supply circuit to operate.

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Why can't UPS use the power of generator?


It doesn't mean it can't be used, but it must match. The UPS with three-phase input shall be connected to the three-phase generator, while the UPS with single-phase input shall be connected to the three-phase generator, so that the load of the generator shall be balanced and the single-phase power shall not be too large.


The output frequency of UPS tracks the input frequency. The frequency and voltage of small brand generators are unstable, so UPS can not bear it. So it is directly added to the load, and the load will burn out, even if there is an online UPS.


The starting current of the generator is too large, the UPS starts to enter the overload state, and the dripping sound sounds (overload alarm). It is recommended to provide another UPS matching the generator power.

Can the generator charge the UPS?

It is not feasible that generator charge UPS.

It needs to install a voltage stabilizer. As the output voltage of the generator is extremely unstable and fluctuates greatly, if it is directly connected to the mains power input of UPS, it will greatly affect the performance of UPS, increase the failure rate of UPS and reduce the efficiency of UPS.


The UPS with low power consumption has the function of power factor correction, which can quickly respond to the changes of mains power. Small generators are also electronically controlled, which can quickly respond to load changes. However, the two are not synchronized, resulting in UPS and generator being constantly adjusted, so that the change rate (not range) of generator output frequency exceeds the allowable frequency change rate of UPS mains input, and the generator power cannot be connected normally.

1. the power of generator is more than 2 times larger than UPS.

2. the output voltage of generator shall reach the acceptable range of input voltage of UPS.

3. the frequency of generator shall reach 50Hz, and none of the three is indispensable.


If the power generated by the generator is not received by the uninterruptible power supply after power failure. In this case, you can try to adjust the generator which the speed is lower to make it adaptive.


If you have more question about UPS and generator, welcome to contact us. We are diesel generator manufacturer in China, founded in 2006. Our diesel generator is low fuel consumption, low noise and small vibration. We have Cummins, Volvo, Perkins, Yuchai, Shangchai, Weichai, Ricardo, MTU, Deutz etc. All diesel generators have passed CE and ISO certificates. If you have purchase plan, welcome to contact us to our email, we will work with you at any time.

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About Dieselgenerator Tech Advanced    ***

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Joined APSense since, December 21st, 2021, From Nanning, China.

Created on Jul 10th 2022 22:52. Viewed 126 times.


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