Yaskawa AC Drive Z1000 AC Drive HVAC Fan - Manual (Page 31)

n b2-13: Short Circuit Brake Time 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. Name Setting Range Default
b2-13 Short Circuit Brake Time at Stop 0.00 to 25.50 s 0.50 s
n b2-18: Short Circuit Braking 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. Name Setting Range Default
b2-18 Short Circuit Braking Current 0.0 to 200.0% 100.0%
u b3: Speed Search
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.
For PM motors, only parameter b3-01 is needed to enable Speed Search.
For induction motors, the drive offers two types of Speed Search than can be selected by parameter b3-24 (Speed Estimation
and Current Detection). Both methods are explained below and followed by a description of all relevant parameters.
n Current Detection Speed Search (b3-24 = 0)
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 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.
Figure 1.10 illustrates Current Detection Speed Search operation after a momentary power loss (L2-01 must be set to 1 or 2):
AC power
supply
Output
frequency
Output
current
OFF ON
Output frequency before
momentary power loss
Selected
frequency
reference
Min. Baseblock Time (L2-03)
Decel time
set to b3-03
Waits for twice
as long as L2-04
Speed Search operation
current set to b3-02
b3-05
Figure 1.10 Current Detection Speed Search after Power Loss
Note: After power is restored, the drive waits until the time set to b3-05 has passed before performing Speed Search. Thereby the Speed Search
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.
1.2 b: Application
YASKAWA ELECTRIC SIEP YAIZ1U 03A YASKAWA AC Drive – Z1000 Programming Manual 31
1
Parameter Details