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b2 1
S ort Circuit Bra e ime at Stop
The Short Circuit Braking described for parameter b2-12 can also be applied at the end of deceleration to completely stop high
inertia loads. Short Circuit Braking is initiated for the time set in b2-13 when the output frequency falls below the higher of
the values b1-02 and E1-09. Disabled when set to 0.00 s.
No
b2-13
b2 18 S ort Circuit Bra in Current
Sets the current level for Short Circuit Braking operation as a percentage of the motor rated current. The Short Circuit Braking
current cannot be higher than 120%, although a higher current level can be set using b2-18.
No
b2-18
b
Speed Searc
The Speed Search function allows the drive to detect the speed of a rotating motor shaft that is driven by external forces and
start the motor operation directly from the detected speed without first stopping the machine.
Example: When a momentary loss of power occurs, the drive output shuts off and the motor coasts. When power returns, the
drive can find the speed of the coasting motor and restart it directly.
Enabling Speed Search for PM motors only requires setting parameter b3-01 to 1.
The drive offers current detection and speed estimation Speed Search for induction motors. Parameter b3-24 selects the speed
search method for induction motors. Both methods and relevant parameters are explained below.
Current Detection Speed Searc (b 2
Current Detection Speed Search detects the motor speed by looking at motor current in IM motors. When Speed Search is
started it reduces the output frequency starting from either the maximum output frequency or the frequency reference while
increasing the output voltage using the time set in parameter L2-04. As long as the current is higher than the level set to b3-02,
the output frequency is lowered using the time constant set to b3-03. If the output current falls below b3-02, the drive assumes
that the output frequency and motor speed are the same and accelerates or decelerates to the frequency reference.
Be aware that sudden acceleration may occur when using this method of Speed Search with relatively light loads.
illustrates Current Detection Speed Search operation after a momentary power loss (L2-01 must be set to 1 or 2):
Figure 1.10
AC power
After power is restored, the drive waits until the time set to b3-05 has passed before performing Speed Search. Thereby the Speed Search
Note:
may start not at the end of L2-03 but even later.
When Speed Search is applied automatically with the Run command, the drive waits for the minimum baseblock time set to
L2-03 before starting Speed Search. If L2-03 is lower than the time set to parameter b3-05, then b3-05 is used as the wait time.
Name
Short Circuit Brake Time at Stop
Name
Short Circuit Braking Current
Output frequency before
momentary power loss
supply
ON
OFF
Output
frequency
Output
current
Min. Baseblock Time (L2-03)
Fi ure 1 1
Current Detection Speed Searc a ter Po er Loss
Settin
0.00 to 25.50 s
Settin
0.0 to 200.0%
)
Decel time
Waits for twice
set to b3-03
as long as L2-04
Speed Search operation
current set to b3-02
b3-05
1 2 b Application
an e
De ault
0.50 s
an e
De ault
100.0%
Selected
frequency
reference
1
1
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