When trucks first came into popular use, nobody would have dreamed of the numerous specialty applications evolving in the ensuing decades. In those days, only a fraction of homes had electricity. Today one is hard put to find a building that does not, thanks to the existence of the electrical power grid. The maintenance of the functionality of the power grid is made possible through the capabilities ofutility trucks and their trained operators.What makes the utility truck so versatile? It is the combination of its hydraulic and electric equipment, designed to perform tasks ranging from lifting people to the tops of poles to drilling holes to support insulators to splicing cable. At the heart of the electrical system are high power chassis mounted DC-DC converters for utility trucks, which transform the power of a 12V DC vehicle system to 24V DC and in some applications as high as 48V DC. The truck comes equipped with a 12V DC power source, so the frequently asked question becomes, “Why an additional DC source?”
Power tools and pump motors for feeding hydraulics require high bursts of electric current (power) over short periods of time. If these bursts had to be supplied by a 12V system, the peak levels of electrical current demanded would result in great inefficiency through losses in the copper cables delivering that current. In such situations, the capabilities of the system would be exceeded and its elements would burn out. To overcome this, many utility trucks have what can be termed a DC Power substation. Figure #1 depicts the principle employing a configuration which converts 12V to 24V.
Batteries #1 and #2 are connected in series to give 24V. They are capable of delivering hundreds of amperes on demand. The DC-DC converter acts as a charger which can deliver moderate currents continuously to keep the battery bank charged and primed to deliver large currents. This method may be scaled to provide even higher currents and voltages. This is the secret power of the utility truck.