cold start

Power equipment may experience a temporary flow of current exceeding specified levels at startup, known as inrush current, which requires countermeasures. Inserting a resistor to suppress inrush current is a simple and inexpensive method, but it has the drawback of decreased efficiency due to resistive losses. To overcome this drawback, there is a cold start method that utilizes a thermistor with the characteristic of decreasing resistance as temperature rises. In a cold start, the large resistance at low temperatures suppresses the inrush current at startup, and as the temperature increases to the operating level, the resistance decreases, reducing losses. However, if the equipment recovers immediately after a brief power outage once it has reached the operating temperature, there is no cooling time for the thermistor, which results in a large inrush current that can negatively affect the equipment.