When we talk about a D.O.L, what comes to mind? When you ask us the same question, our minds immediately go to the simplest and most traditional type of start: Direct On Line.
In simple terms, a D.O.L start means to connect the motor directly to the power supply to perform a full-voltage start-up. When the rotor is high, it induces a current which results in a peak current on the network – often 5 to 8 times the nominal current. A D.O.L start is the most cost-effective system for starting pumps and motors, so it makes sense that is the most widely used solution.
When to use a D.O.L?
D.O.Ls are perfect for the start-up of small submersible pumps, deep well pumps or booster sets with surface pumps. However, it’s important to ensure that the control panels are directly connected to the power supply network, which means it:
- Starts at full voltage
- Maintains a constant frequency
- Has a high starting torque
- Has very short acceleration times
D.O.L in Practice
When a pelletising plant in Rustenburg approached us to replace their panels, we knew they would require high torque D.O.Ls. We therefore supplied them with two D.O.L starter panels, one 11kW and one 30kW D.O.L panel.
Working closely with our partner in excellence, Siemens, we were able to procure all the low-voltage switchgear for the panels, that included the following: SIRIUS 3RV2 Motor Starter Protectors, SIRIUS 3RT Contactors and Aux, SENTRON Miniature Circuit Breakers, LZS Coupling Relays and Bases and, of course, our trusty SIMOCODE Motor Protection.
Once we procured the components, it was time to start designing. For this project, we teamed up with our long-term Siemens System Integrator, Afrilek Automation. They assisted us in designing a solution where we could implement these Siemens products into the D.O.L starter panels with exceptional speed.
Despite the delays in shipment and delivery experienced across the world, Lasrust Enterprises still managed to deliver a holistic solution – on time and within budget.
CURRENT STATUS: Our client has received the panels, and we are now moving into the installation and commissioning phase – truly, a work of engineering art!
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