Hanbell RC2-930A - 5. Electrical data and design; 5.1 Motor design

Technical Manual VERSION 2.0 -10-18-2018
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5. Electrical data and design 
5.1 Motor design
HANBELL RC2 series screw compressors are fitted with Y∆ motor as standard. But ∆/∆∆ motor (Part Winding
Starting – PWS) is also available for model RC2100A ~ RC2580A & RC2100B ~ RC2580B.
i.e. ●RC2100A ~ RC2580A & RC2100B ~ RC2580B both Y∆ motor and ∆/∆∆ motor are available.
●RC2620A ~ RC21530A & RC2620B ~ RC21530B only Y∆ motor are available.
Y∆ Starting
Y∆ 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.
Y∆ motor connection method is shown in the following motor wiring diagram:
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.
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Full load Amper
Starting
Current
Time
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Y shift time 0.25~0.5sec
Figure 54 Y∆ Starting diagram
Attention! : After Y start, MCM & MCS are deductive for 0.25 sec and then MCM & MCD are inductive for ∆ run. Within
as transient as 0.25 sec, pseudo short circuit might occur due to inappropriate action of contactors, causing trip of
compressors. When it occurs, we recommend usage of adjustable Y∆ dedicated timer or slightly lengthen span of
time for MCM, MCS deduction  MCM, MCD reinduction from 0.25 sec to 0.5 sec max directly in micro controller or
PLC program. Please refer to Y∆ shift time diagram for details. Because motor is not powered during Y∆ shift,
shorter Y∆ shift span is suggested to prevent second start due to decreased rotation speed. However, if Y∆ shift
span is too short, aforementioned pseudo short circuit might occur.
Characteristics of Y∆ Starting
1. Starting current in Y connection is 1/3 of lock rotor ampere.
2. Starting torque in Y connection is 1/3 of lock rotor torque.
3. Acceleration of motor rotor becomes smaller at fullload starting, therefore compressors require starting at partial
load.
B:Pt100 / Pt1000(Option)
A:PTC
A
Earth Bolt
B
V
W
Y
X
Z
U
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