Transient currents are commonly read during star-delta switching.
Utilization
During the initial starting phase ("star" connection), the resistive torque of the driven machine must remain, irrespective of speed, less than the
"star" motor torque until "star-delta" switching occurs.
This starting mode is therefore ideal for machines with no-load starting:
– machine-tools,
– centrifugal compressors,
– wood working machines, etc.
In order to prevent a high current peak, at least 80 - 85 % of
nominal speed must be reached before switching from star to
delta.
Precautions
Motor nominal voltage in delta connection must be equal to that of the mains.
Example:
A motor for 400 V star-delta starting must be designed for 400 V in
"delta" connection. Its usual designation is "400 V / 690 V motor". The motor must be constructed with 6 terminal windings.
Sequence
Starting is a three-stage process:
1st stage - "Star" connection
Press the "On" button on the control circuit to close the KM2 "star" contactor. The KM1 "line" contactor then closes and the motor starts.
Countdown of programmed starting time (normally 6 to 10 s) then begins.
2nd stage - "Star" to "Delta" switching
When the programmed starting time is over, the KM2 "star" contactor opens.
3rd stage - "Delta" connection
A transition time (or dwelling time) of 50 ms is fixed between opening of the "star" contactor and closing of the "delta" contactor by the use of TE5S timer. This prevents short circuit between "star" and "delta".
Note: When AF... contactor types are used as delta and star contactors or an A... contactor as star contactor with an AF... contactor as delta contactor, the use of a timer including a dwelling time (or transition time) e.g. TE5S or similar is not necessary. A timer set for the starting duration in star connection is enough. An electrical interlock between star and delta is mandatory such as VE 5 or through auxiliary contacts.
Furthermore, in open transition, the current interruption may reach up to 95 ms: it shall be checked that this duration is compatible with the application i.e. mainly if the decreasing in rotation speed is acceptable during the starting phase.
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2/18
Connection Bars for Contactor and MCCB
Connection Bars for Contactor and Switch fuse
Application
Connections between contactors/starters and moulded case circuit breakers or switch fuses.
Description
These connection sets are solid copper bars either isolated or protected by shrouds.
Connection bars between contactor and MCCB
Vertical assembly
Contactors
MCCB
Weight
Order code
kg
A 145, A 185
T 3
0.150
BEA 185/T3
A 145, A 185
S 3, S 4
0.150
BEA 185/S3/S4
A 210
S 4
0.160
BEA 210/S4
A 300-30 contactor + MCCB on top
A 210 ... A 300
S 5
0.200
BEA 300/S5
AF 400, AF 460
S 5
0.250
BEA 400/S5
AF 400 ... AF 750
S 6
0.410
BEA 750/S6
Vertical assembly with control wire terminals (Also suitable when using busbar kits for starter combinations) A 145, A 185
T 3
0.175
BEA 185 D/T3
A 145 ... A 185
S 3, S 4
0.200
BEA 185D/S3/S4
A 210
S 4
0.270
BEA 210D/S4
A 210 ... A 300
S 5
0.320
BEA 300D/S5
BEA 300/S5
AF 400, AF 460
S 5
0.480
BEA 400D/S5
AF 400 ... AF 750
S 6
0.720
BEA 750D/S6
Horizontal assembly (Also suitable when using busbar kits for starter combinations) A 145, A 185
S 3, S 4
0.520
BEA 185H/S4
A 210
S 4
0.620
BEA 210H/S4
A 210, A 300
S 5
1.280
BEA 300H/S5
AF 400, AF 460
S 5
1.310
BEA 400H/S5
AF 400, AF 460
S 6
2.450
BEA 460H/S6
AF 580, AF 750
S 6
4.010
BEA 750H/S6
BEA...D/S
Note: The BEA... connection bars provided for the A 145 ... A 300 contactors can be used for the AF 145 ... AF 300 contactors.
Connection bars between contactor and switch fuse
Vertical assembly
Contactors
Switch fuse
Weight
Order code
kg
1 piece
A 185
OESA 250
0.260
A210 ... A 300
OESA 250 to
0.330
BEF 185/OESA250
OESA 400
BEF 300/OESA400
AF 400 ... AF 460
OESA 400
0.340
BEA 300H/S5
AF 460 ... AF 750
OESA 630 to
0.740
BEF 460/OESA400
OESA 800
BEF 750/OESA800
Horizontal assembly
A 145
OS 160..LR
0.170
OSZA 15
A 145, A 185
OESA 250..LR
0.550
BEF 185H/OESA250
A 210 ... A 300
OESA 250..LR to
BEF 300H/OESA400
BEF 300/OESA400
OESA 400..LR
AF 400, AF 460
OESA 400..LR
1.250
BEF 460H/OESA400
Note: The BEF... connection bars provided for the A 145 ... A 300 contactors can be used for the AF 145 ... AF 300 contactors.
BEF 300H/OESA400
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ABB LIMITED
2/19
A.., AF.., 4-pole Contactors
a.c. Circuit Switching
A 9
A 16
A 26
Switching of Resistive Circuits
AC-1 utilization category
Rated
< 40 °C
A
25
30
45
When
m a k i n g,
AC-1 operational
< 55 °C
A
22
27
40
the switched-on
current
< 70 °C
A
18
23
32
current is equal
to the In l o a d