To load inverter/UPS is not like to connect appliance with wall socket. You can only connect loads to inverter/UPS which do not exceed its rated power (e.g. you can not connect a 300W computer to a 150W inverter). If you erroneously try to connect loads bigger than its rated power, it would get damaged without protection. But with built-in overload protection, inverter/UPS will just simply won't start or stop running without any damage. After a few seconds, inverter/UPS will try to start again automatically if surplus loads are removed; if not, inverter/UPS will switch off again. After a certain number of attempts, inverter/UPS will shut down; then user must operate button panel to restart manually. There is a difference between continuous and short time overload where the latter means that overload condition is present (few milliseconds or second). For example, water pump, refrigerator, microwave….which require a very big current when start up than their rated power, inverter/UPS can take up to 200% overload for a short time.