Star–delta starter guides

CHIEF. LEARN · 6 guides

The theory behind the Star–Delta Connection simulator, one topic per page: what the starter does, why ships use it, how to set it and what goes wrong.

The example throughout is the main fire pump of a platform supply vessel: a 37 kW cage motor on a 440 V, 60 Hz supply, full-load current 61 A, started star–delta from the main switchboard.

  1. 01How a star–delta starter worksStar and delta on a 440 V ship’s supply: why a cage motor draws six times its full-load current, and how a star start cuts it to a third at a third of the torque.
  2. 02Motor starting and generator voltage dipHow far a motor start pulls a ship’s generator voltage down, the estimate x·k ÷ (1 + x·k), and the limits in IACS UR E5, UR E13 and IEC 60947-4-1.
  3. 03Star–delta changeover: timer setting and interlockThe star–delta changeover step by step, how to set the timer (80–90 % of synchronous speed) and why the star and delta contactors must never close together.
  4. 04Overload relay setting and direction of rotationWhy a star–delta overload relay is set to FLC ÷ √3 = 0.58 × FLC, how a fire pump ends up turning backwards, and how to reverse a star–delta motor safely.
  5. 05Starting methods on board: DOL, star–delta, soft starter, VFDDirect-on-line, star–delta, soft starter or frequency converter on a ship, and what a starter does after a blackout: low-voltage protection (LVP) or release (LVR).
  6. 06The fire main isolating valve and the emergency fire pumpWhy the engine room part of the fire main has an isolating valve (SOLAS II-2/10), how the emergency fire pump and SDNR valves work together, and the test.

Faults and what they look like

Most starter faults show up in three places at once: the ammeter, the sound of the motor and the pressure gauge. Read them together before you open anything.

Isolate, lock off and test for dead before you touch the starter or the terminal box. A 440 V motor terminal does not forgive.

In the simulator’s fire drill most situations hide one fault, electrical or on the fire main. The routine drill hides none, and the exam can pick it like any other.