Explanation:
In this test we will simulate the transformer being switched off. The generators will start and take over the power. The UPS systems will handle the temporary loss of power, this will not affect the customer.

Risk:
Due to the switching, there is a risk of a short interruption in the main power supply when switching on and off. Experience shows that this does not actually occur. The UPS systems will absorb this possible short interruption so that you will not notice it in your rack.