SUBMERSIBLE PUMPS BASIC INFORMATION AND DIAGRAM

PARTS OF SUBMERSIBLE PUMP

figure 1

A submersible pump consists of a centrifugal pump driven by an electric motor. The pump and the motor are contained in one housing, submersed below the permanent water level, within the well casing.

The pump housing is a cylinder 3–5 in. in diameter and 2–4 ft long. When running, the pump raises the water upward through the piping, to the water tank. Proper pressure is maintained in the system by a pressure switch. The disconnect switch, pressure switch, limit switches, and controller, are installed in a logical and convenient location near the water tank.

Pumps commonly called “2-wire pumps” contain all required starting and protection components and connect directly to the pressure switch—with no other aboveground controller. Generally, there are no moving electrical parts within the submersible pump, such as the centrifugal starting switch found in a typical single-phase, split-phase induction motor.

Other pumps, referred to as “3-wire pumps,” require an aboveground controller that contains any required components not in the motor, such as a starting relay, overload protection, starting and running capacitors, lightning arrester, and terminals for making the necessary electrical connections.

Most water pressure tanks have a precharged air chamber in an elastic bag (bladder) that separates
the air from the water. This ensures that air is not absorbed by the water. Water pressure tanks compress air to maintain delivery pressure in a usable range without cycling the pump at too fast a rate.

When in direct contact with the water, air is gradually absorbed into the water, and the cycling rate of
the pump will become too rapid for good pump life unless the air is periodically replaced. With the elastic
bag, the initial air charge is always maintained, so recharging is unnecessary.

Submersible pumps are covered by UL Standard 778.

Submersible Pump Cable
Power to the motor is supplied by a “drop” cable, especially designed for use with submersible pumps. This cable is marked “submersible pump cable,” and it is generally supplied with the pump.

This cable can also be purchased separately. The cable is cut to the proper length to reach between the pump and its controller, as shown above (figure 1) or between the pump and the well cap, as shown below:

When needed, the cable may be spliced according to the manufacturer’s specifications. Submersible water pump cable is “tag-marked” for use within the well casing for wiring deep-well water pumps, where the cable is not subject to repetitive handling caused by frequent servicing of the pump units.

A submersible pump cable is not designed for direct burial in the ground unless it is marked “Type USE” or “Type UF.” Should it be required to run the pump’s circuit underground for any distance, it is necessary to install Type UF or Type USE cable or a raceway with suitable conductors, and then make up the necessary splices in a listed weatherproof junction box.