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Protective Functions
Preventing Motor Stalling During Operation
Stall prevention during operation prevents the motor from stalling by automatically lowering the inverter output frequency when a transient overload occurs while the motor is operating at a constant speed.
Stall prevention during operation can be enabled in V/f control only. If the Inverter output current continues to exceed the setting in parameter L3-06 for 100 ms or longer, the motor speed is reduced. Enable or disable the stall prevention using parameter L3-05. Set the according deceleration times using C1-02 (Deceleration time
1) or C1-04 (Deceleration Time 2).
If the Inverter output current reaches the set value in L3-06 – 2%, the motor will accelerate again to the set frequency.
Related Parameters
Parameter
No.
Name
L3-05
L3-06
Stall prevention selection during running function selection
Stall prevention level during running
Factory
Setting
Change during
Operation
1
150%
No
No
V/f
Control Methods
Open
Loop
Vector
Closed
Loop
Vector
A No No
A No No
Precautions
If the motor capacity is smaller than the Inverter capacity or the motor stalls when operating at the factory settings, lower the stall prevention level during operation.
Setting Precautions
•
•
•
•
Set the parameters as a percentage taking the inverter rated current to be 100%.
Do not increase the stall prevention level unnecessarily. An extremely high setting can reduce the inverter lifetime. Also do not disable the function.
If the motor stalls with the factory settings check the V/f pattern (E1-) and the motor setup (E2-).
If the stall level has to be increased very much to get the elevator running check the mechanical system or consider to use a one size bigger inverter.
Motor Torque Detection / Car Stuck Detection
The inverter provides a torque detection function to detect overtorque (Car stuck) or undertorque. An alarm signal can be output to the digital output terminals M1-M2, M3-M4, or M5-M6.
To use the overtorque/undertorque detection function, set B, 17, 18, 19 (overtorque/undertorque detection
NO/NC) in one of the parameter H2-01 to H2-03 (digital output terminals M1 to M6 function selection).
Overtorque/undertorque is detected by:
•
observing the output current in V/f control (the inverter rated output current is equal to 100%).
•
observing the torque reference value in Open Loop and Closed Loop Vector control (the motor rated torque is equal to 100%).
Protective Functions
Related Parameters
Parameter
No.
L6-01
L6-02
L6-03
L6-04
L6-05
L6-06
Name
Torque detection selection 1
Torque detection level 1
Torque detection time 1
Torque detection selection 2
Torque detection level 2
Torque detection time 2
Factory
Setting
Change during
Operation
4
150%
10.0 s
0
150%
0.1 s
No
No
No
No
No
No
A
A
A
Control Methods
V/f
Open
Loop
Vector
Closed
Loop
Vector
A A A
A
A
A
A
A
A
A
A
A
A
A
A
Multi-function Output (H2-01 to H2-03)
Set
Value
B
17
18
19
Function
Overtorque/undertorque detection 1 NO
(NO contact: Overtorque detection and undertorque detection enabled when contact is ON)
Overtorque/undertorque detection 1 NC
(NC contact: Overtorque detection and undertorque detection enabled when contact is OFF)
Overtorque/undertorque detection 2 NO
(NO contact: Overtorque detection and undertorque detection enabled when contact is ON)
Overtorque/undertorque detection 2 NC
(NC contact: Overtorque detection and undertorque detection enabled when contact is OFF)
Yes
Yes
Yes
Control Methods
V/f
Open
Loop
Vector
Close d Loop
Vector
Yes Yes Yes
Yes
Yes
Yes
Yes
Yes
Yes
L6-01 and L6-04 Set Values and Operator Display (JVOP-160 only)
The relationship between alarms displayed on the digital operator when overtorque or undertorque is detected, and the set values in L6-01 and L6-04, is shown in the following table.
Set
Value
0
1
2
3
4
5
6
7
8
Function
Operator Display
Overtorque/
Undertorque
Detection 1
Overtorque/
Undertorque
Detection 2
– – Overtorque/undertorque detection disabled.
Overtorque/Car stuck detection only with speed agree; operation continues (warning is output).
Overtorque/Car stuck detected continuously during operation; operation continues
(warning is output).
Overtorque/Car stuck detection only with speed agree; output is stopped upon detection.
OL3 flashes
OL3 flashes
OL3 lights up
OL4 flashes
OL4 flashes
OL4 lights up
Overtorque/Car stuck detected continuously during operation; output is stopped upon detection.
OL3 lights up
Undertorque detection only with speed agree; operation continues (warning is output).
UL3 flashes
OL4 lights up
UL4 flashes
Undertorque detected continuously during operation; operation continues (warning is output).
UL3 flashes UL4 flashes
Undertorque detection only with speed matching; output is stopped upon detection.
UL3 lights up UL4 lights up
Undertorque detected continuously during operation; output is stopped upon detection.
UL3 lights up UL4 lights up
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Timing Charts
Fig 5.43
and
Fig 5.44
show the timing charts for overtorque and undertorque detection.
Motor current (output torque)
L6-02 or L6-05
Overtorque detection 1 NO or overtorque detection 2 NO
L6-03 or
L6-06
L6-03 or
L6-06
*Overtorque detection switch off bandwidth is approximately 10% of the Inverter rated output current
(or motor rated torque).
Fig 5.43 Overtorque Detection
Motor current (output torque)
L6-02 or L6-05
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36
Undertorque detection 1 NO or undertorque detection 2 NO
L6-03 or
L6-06
L6-03 or
L6-06
*Undertorque detection switch off bandwidth is approximately 10% of the Inverter rated output current (or motor rated torque).
Fig 5.44 Undertorque Detection
Car Stuck Detection (OL3, Using Overtorque detection)
The Overtorque detection function can be used to detect a stuck car. The torque detection function 1 can be used for this. Therefore a digital output has to be programmed for “Overtorque detection 1” (H2- = B or
17). Using this with the factory setting car stuck is detected (output is switched) torque/current is higher than
150% for 10 sec. The level can be adjusted in L6-02, the time in L6-03. The output is switched of and an OL3
fault will be indicated (see
Fig 5.45
)
DC Injection/ zero servo speed
Inverter enable (D/I)
Up/Down (D/I)
Selected Speed (D/I)
Fault
Torque is higher than L6-02 detect. time
L6-03
Fig 5.45 Car Stuck fault detection
Protective Functions
Limiting Motor Torque (Torque Limit Function)
This function allows limitation of motor shaft torque independently for each of the four quadrants. The torque limit can be set as fixed value using parameters or as variable value using an analog input. The torque limit function can be used with Open Loop Vector and Closed Loop Vector control only.
Related Parameters
Parameter
No.
Name
L7-01
L7-02
L7-03
L7-04
L7-06
L7-07
Forward drive torque limit
Reverse drive torque limit
Forward regenerative torque limit
Reverse regenerative torque limit
Torque limit time constant
Torque limit operation during accel./decel.
* A setting value of 100% is equal to the motor rated torque.
Multi-function Output (H2-01 to H2-03)
Set
Value
Function
30 During torque limit
Factory Setting
Change during Operation
300%*
300%*
300%*
300%*
200 ms
0
No
No
No
No
No
No
No
No
No
No
V/f
Control Methods
Open
Loop
Vector
Closed
Loop
Vector
No
No
A
A
A
A
A
A
No
No
A
A
A
A
V/f
No
Control Methods
V/f with
PG
Open
Loop
Vector
No Yes
Closed
Loop
Vector
Yes
Setting the Torque Limit Using Parameters
Using L7-01 to L7-04, four torque limits in the following directions can be set individually: Forward drive, reverse drive, forward regenerative and reverse regenerative (see
Fig 5.46
)
Output Torque
L7-01
L7-04
Reverse
Regenerative
Forward
Drive
Output Speed
Reverse
Drive
Forward
Regenerative
L7-03
L7-02
Fig 5.46 Torque Limit Parameters
Using a Digital Output to Signalize Operation at the Torque Limit
If a multifunction output is set for this function (H2-01 to H2-03 is set to “30”), the output is switched ON when the motor output torque reaches one of the torque limits.
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Enabling Integral Torque Limit Operation (L7-06 and L7-07)
In Open Loop Vector control an integral operation can be applied to the torque limit function (P-control is standard). This improves the torque limit responsiveness and smoothes the torque limit operation. To enable the integral operation set parameter L7-07 to 1. The integral time constant can be set in parameter L7-06.
Setting Precautions
•
•
When the output torque reaches the torque limit, control and compensation of the motor speed is disabled to prevent the output torque from exceeding the torque limit. The torque limit has the priority.
The torque limit accuracy is ±5% at an output frequency of 10 Hz or above. When output frequency is lower than 10 Hz, the accuracy is lowered.
Motor Overload Protection
The motor can be protected from overload using the built-in electronic thermal overload relay function.
Related Parameters
Parameter
No.
E2-01
L1-01
L1-02
Motor rated current
Name
Motor protection selection
Motor protection time constant
Factory
Setting
1.90 A *
1
1.0 min
Change during
Operation
No
No
No
* Factory settings depend on Inverter capacity. (The values shown are for a 200 V Class Inverter with 0.4 kW.)
V/f
Control Methods
Open
Loop
Vector
Closed
Loop
Vector
Q Q Q
Q
A
Q
A
Q
A
Multi-Function Outputs (H2-01 to H2-03)
Set
Value
Function
Control Methods
V/f
Open
Loop
Vector
Closed
Loop
Vector
1F Motor overload (OL1, including OH3) pre-alarm (ON: 90% or more of the detection level) Yes Yes Yes
Setting Motor Rated Current (E2-01)
Set the rated current value on the motor nameplate in parameters E2-01 (for motor 1). This set value is the base current for the internal thermal overload calculation.
Setting Motor Overload Protection Characteristics (L1-01)
Set the overload protection function in L1-01 according to the used motor.
The induction motor's cooling abilities vary with the motor type. Consequently, you must select the electronic thermal protection characteristics.
Set L1-01 to:
0: to disable the thermal motor protection function.
1: to enable the thermal motor protection for a fan cooled general purpose motor (self-cooled).
2: to enable the thermal motor protection for an inverter motor (externally cooled).
3: to enable the thermal motor protection for a special vector motor (externally cooled).
Protective Functions
Setting Motor Protection Operation Time (L1-02)
The motor protection operation time is the time for that the motor can handle a 150% overload when it was running with the rated load before (i.e. operating temperature was reached before applying the 150% overload). Set the motor protection operation time in L1-02. The factory setting is 60 sec.
Fig 5.47
shows an example of the characteristics of the electronic thermal protection operation time (L1-02 =
1.0 min., operation at 50 Hz, general-purpose motor characteristics, when L1-01 is set to 1)
Operating time (min.)
Cold start
Hot start
Motor current (%)
E2-01 is set to 100%
Fig 5.47 Motor Protection Operation Time
Setting a Motor Overload Pre-Alarm
If the motor overload protection function is enabled (i.e., L1-01 is set to a value different from 0) and H2-01 is set to H2-03 (output terminals M1-M2, M3-M4, and M5-M6 function selection) to 1F (motor overload OL1 pre-alarm), the motor overload pre-alarm will be output at. If the electronic thermal value reaches minimum
90% of the overload detection level, the output terminal that has been set will be turned ON.
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Output Current Observation
The inverter can observe the output current and thereby detect if something is wrong in the sequence or with the motor connection. There are two observer functions, one for the start and one during run.
Related Parameters
Parameter
No.
S1-14
S1-15
SE2 detection time
SE3 detection time
Name
Factory
Setting
200 ms
200 ms
Change during
Operation
No
No
V/f
Control Methods
Open
Loop
Vector
Closed
Loop
Vector
A A A
A A A
SE2 fault (SE2, Current observation at start)
At the brake open delay time (S1-06) + S1-14 after the Up/Down command was given, the output current is measured. If it is below 25% of the motor no-load current (E2-03) a SE2 fault will be output.
SE3 fault (SE3, Current observation during Run)
From the time S1-15 after the Up/Down command was given, the inverter starts to observe the output current continuously. If it falls below 25% of the motor no-load current (E2-03) a SE3 will be output.
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