Hanbell RC2-100AF, Manual

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5. Electrical data and design
5.1 Motor design
HANBELL RC2-F series screw compressors are fitted with Y-
Δ motor as standard. But Δ/ΔΔ motor (Part Winding
Starting
– PWS) is also available for model RC2-100F ~ RC2-580F.
i.e.
● RC2-100F ~ RC2-580F both Y-Δ motor and Δ/ΔΔ motor are available.
● RC2-620F ~ RC2-1530F only Y-Δ motor are available.
Y-
Δ Starting
Y-
Δ motor connects motor coil by Y connection during starting therefore reducing voltage on coils to 1/√3 of input
voltage and reconnects motor coil by
△
connection after starting. By doing so, we can decrease starting current
thorough voltage drop, i.e., so-called voltage-drop starting.
In Y connection, MCM
、
MCS are inductive while motor leads Z,X,Y are tied together as a neutral connecting as Y
fashion. A few seconds later ( 3 ~ 5 sec is recommended), MCM, MCS become deductive. Around 0.25 sec later,
MCM,MCD are inductive
，
it turns out
△
run connection. Y-
Δ motor connection method is shown in the following
motor wiring diagram:
Full load Amper
Starting Current
Time
I
(AMP)
Y- shift time 0.25~0.5msec
Please pay attention : After Y start
，
MCM & MCS are deductive for 0.25msec and then MCM & MCD are inductive
for
Δ run. Within as transient as 0.25msec, pseudo short circuit might occur due to inappropriate action of
contactors, causing trip of compressors. When it occurs, we recommend usage of adjustable Y-
Δ dedicated Timer
or slightly lengthen span of time for MCM, MCS deduction - MCM,MCD re-induction from 0.25 msec to 0.5 msec
max directly in micro controller or PLC program. Please refer to Y-
Δ shift time diagram for details. Because motor
is not powered during Y-
Δ shift, shorter Y-Δ shift span is suggested to prevent second start due to decreased
rotation speed. However, if Y-
Δ shift span is too short, aforementioned pseudo short circuit might occur.