Inserting Alarm System to an Oil Pump Control Circuit

At some point in time, you may happen to have an old industrial pump unit wired inside an existing control panel that would require circuit modification in order to include an alarm system. What is being referred to here are pump systems most commonly found in industrial facilities such as oil pump, hydraulic pump, grease pump, water pump, air pump or air compressors, but nevertheless, the electrical circuit presented in this article may also be used to set an example to provide idea for other similar applications.

In heavy industrial facilities, one of the important foundation of a good working machinery is dependent on the condition of a well-oiled mechanism. This pertains to having a reliable lubrication system that ensures all moving parts of every machinery in the factory are well-lubricated in order to diminish friction and grinding on the machine's mechanical joints and contacts.

Absence of oil lubrication in the event of a pump failure will totally wreck the machine, and to make matters worse, it will cause the machine to sustain irreparable damage. But there are many ways to detect pump failure even before the oil distribution ceases to flow and runs out in the machine, this is done by means of checking evidences attributed to the exhibited symptoms associated with pump failures which serves as critical warning points at various stages in the correlated members of the pump assembly.

The associated factors attributed to the function that indicates the presence of oil distribution in a working pump system involves flow, pressure, level and temperature. These functions can be used as determinants to detect oil distribution loss and pump failure. Devices that operate as sensors specific to each of these functions are installed at corresponding locations in the pump system that sends signal to the alarm circuit in the event of pump failure.

The electrical diagram on Figure 1 below shows a typical alarm system inserted to the control circuit of an oil pump system.

Figure 1: Electrical diagram of oil pump control circuit modified to include an alarm system inserted to the circuit.

The electrical sensors that are inserted in the oil pump's control circuit includes an oil temperature switch, oil pressure switch, oil level switch and oil flow switch. These devices are remotely installed where the pump assembly is located, which is away from the control panel. Remote to local connection is made possible by electrical cables laid in pipes and cable trench in the factory floor which serves as field wiring connection between the sensors that are mounted remotely in the field and the control circuit wired inside an electrical cabinet.

The buzzer and the warning light will be activated in case any of the four sensors that are connected together in parallel switches ON, individually or simultaneously, whichever of the four sensor energizes to close their respective contacts connected to the buzzer and the warning light.

Oil pressure and oil flow alarm is activated in two different conditions, the first condition is when the main circuit breaker is switched ON first thing before running the machines, which is the most common standard operational procedure in every industrial facility, which will cause the buzzer to sound off due to the initial absence of oil flow and oil pressure. But once the oil pump motor is started, oil pressure and oil flow builds up in the lubrication system going to the machines which will eventually shut-off the alarm. The second condition of alarm activation for these two function is the detection of oil pressure or oil flow drop while the pump is running.

Oil loss warning alarm will also be activated when the amount of oil inside the reservoir tank falls below a required operational level or a minimum level which is detected by the oil level switch installed inside the reservoir tank. The oil temperature switch will also sound the alarm upon detection of abnormal oil temperature.

Each alarm switches is accompanied with an indicator light wired individually so that each indication is specific only to one alarm switch for easy identification as to which of the four alarms are set-off. A lamp test switch is also included in the circuit to check for any malfunctioning indicator lights prior to the operation of the alarm circuit.