LT-S-(L) Technical manual
6.
Electrical Design
6.1
Electrical parameters and design
Motor Design
The standard starting method of Hanbell LT series screw compressor is Y-Δ
start.
6.1.1
Y-Δ Start
The starting mode of
Y-Δ
connection is a Y connection during starting, and the voltage on
the winding is reduced to 1/ 3 of the input voltage. When it completes the starting process, it
will resume to
△
connection. By doing so, we can decrease starting current through
voltage drop, i.e., so-called voltage-drop starting.
The wiring of Y-Δ starting is shown as follow:
In Y connection, MCM, MCS are energized to make Z, X, Y three points
together and become the center point of Y connection. A few seconds (3~5 seconds is
recommended), MCM, MCS converts. About 0.25 seconds later, MCM, MCD are
energized to convert to Δ connection.
Caution:
After Y mode starting, 0.25 seconds after MCM & MCS complete conversion
process, MCM & MCD are energized for Δ running. Pseudo short circuit might occur
within 0.25 seconds due to improper action of the contactor, causing trip of the
MCD
