TrqPrv-Para-Descrip[2].doc

PF700VC
TORQUE PROVING (LIFTING) PARAMETER DESCRIPTIONS

Drive: PF700 AC Vector drive with standard Crane & Hoist Duty firmware version 4.001 or newer,

Lifting Torque / Brake Proving
The Lifting/Torque Proving feature of the PowerFlex 700 is intended for applications where proper coordination between motor control and a mechanical brake is required. Prior to releasing a mechanical brake, the drive will check motor output phase continuity and verify proper motor control (monitoring “torque proving” including current feedback). The drive will also verify that the mechanical brake has control of the load prior to releasing drive control (brake proving). After the drive sets the brake, motor movement is monitored to ensure the brakes ability to hold the load.
Lifting Application functionality includes:
² Torque Proving (includes flux up, use of the last torque measurement including current feedback monitoring).
² Brake Proving (includes mode to slowly lower load if brake slips or fails).
² Float Capability
² Micro-Positioning
² Fast Stop
² Speed Deviation Fault, Output Phase Loss Fault, Encoder Loss Fault.
The Lifting/Torque Proving feature is only available in Vector firmware versions 3.xxx and later. It is intended to operate in the FVC Vector Control mode (see [Motor Cntl Sel], parameter 053) with an encoder. Motor movement is monitored through the encoder feedback which excludes the other feedback modes from being used unless a specific set of steps are followed in order to set up for encoderless operation. Extreme thought and care must be exercised when choosing to set up encoderless operation.

Lifting/Torque Proving Application Programming
The PowerFlex 700 lifting application is mainly influenced by parameters 600 through 611 in the Torque Proving group of the Application file. The paragraphs that follow describe programming.
Figure 0.2 Torque Proving Flow

Torque Proving
When the drive receives a start command to begin a lifting operation, the following actions occur:
1. The drive first performs a transistor diagnostic test to check for phase-to-phase and phase-to-ground shorts. A failure status from either of these tests will result in a drive fault and the brake relay will NOT be energized (brake remains set).
2. The drive will then quickly provide the motor with flux current as well as perform a check for current flow through all three motor phases. This ensures that torque will be deliverable to the load when the mechanical brake is released. When torque proving is enabled, output phase loss detection is performed regardless of the setting of Bit 12 of [Fault Config 1], parameter 238.
3. If the drive passes all tests, the brake will be released and the drive will take control of the load after the programmed time in [Brk Release Time], parameter 604 which typically should be equivalent to the mechanical release time of the brake, for the fastest cycle time.
No.
Name
Value
Notes
238
Fault Config 1
4426
Bit 8 “In Phase Loss” = 1
Bit 12 “Output Phase Loss” = 1
604
Brake ReleaseTime
0.01 Sec.

Brake Proving
When the drive receives a stop command to end a lifting operation, the following actions occur. The brake is commanded closed when the speed of the motor reaches zero.
2. After the time period programmed in [Brk Set Time], parameter 607, typically should be equivalent to the mechanical re-engagement time of the brake. The drive will verify if the brake is capable of holding torque. It will do this by ramping the torque down at a rate set in [TorqLim SlewRate], parameter 608. Note that the drive can be started again at any time without waiting for either of the above timers to finish. Because this VDL is a high speed repetitive application, from previous testing Parameters 607 and 608 were set to :
No.
Name
Value
Notes
607
Brk Set Time
0.10 Sec.

608
TorqLim SlewRate
1.0 Sec.

3. While the torque is ramping down, the drive will perform a brake slip test. If movement exceeds the limit set in [BrkSlip Count], parameter 609, then an alarm is set and the drive will start a brake slip procedure. The drive will allow the motor to travel the distance programmed in [Brk Alarm Travel], parameter 610. So in the event of a mechanical brake failure, another slip test will be performed and will repeat continuously until; A) the lift operator intervenes by realizing there is a brake failure, operates the lift to bring the load to rest on a surface that will support its weight, and shuts down operation B) the load stops slipping, brake holding capability becomes effective or C) the load ends up resting on a surface that will support its weight. This feature keeps control of the load and returns it to rest in a controlled manner.
No.
Name
Value
Notes
609
BrkSlip Count
10

610
Brk Alarm Travel
1.0 Rev.

Speed Monitoring / Speed Band Limit
This routine is intended to fault the drive if the difference between the speed reference and the encoder feedback is larger than the value set in [Spd Dev Band], parameter 602 and the drive is NOT making any progress toward the reference. [SpdBand Integrat], parameter 603 sets the time that the speed difference can be greater than the deviation band before causing a fault and setting the brake. Determine through experimentation the best values for Parameters 602 and 603 to insure proper protection without nuisance Speed Deviation faults. Based on a test installation these values are recommended to begin with.
No.
Name
Value
Notes
602
Spd Dev Band
3.0

603
Spd Band Integrator
100 mSec.

Float
Float is defined as the condition when the drive is holding the load at zero hertz while holding off the mechanical brake. The float condition starts when the frequency drops below the speed set in [Float Tolerance], parameter 606. Float will stay active for a period of time set by [ZeroSpdFloatTime], parameter 605. If a digital input (parameters 361-366) is set to “Micro Pos” (also Float) and it is closed, the Float condition will stay active and will disregard the timer. This signal is also available through a communication device, see [TorqProve Setup], parameter 601. Since the Float feature is not used on VDL lifts set the values to minimum.
No.
Name
Value
Notes
605
ZeroSpdFloatTime
0.10 Sec.

606
Float Tolerance
1.0

Micro Position
Micro Position refers to rescaling of the commanded frequency by a percentage entered in [MicroPos Scale %], parameter 611. This allows for slower operation of a lift which provides an operator with better resolution when positioning a load. Micro Position is activated only when the drive is running at or near zero speed. This can be initiated by a digital input configured as Micro Pos or through a communication device [TorqProve Setup] which is the same digital input that signals the float condition. This was not used on the VDL so values are left as default.
Fast Stop
Fast Stop is intended to stop the load as fast as possible, then set the mechanical brake. The Fast Stop can be initiated from a digital input or through a communication device through [TorqProve Setup]. The difference from a normal stop is that the decel time is forced to be 0.1 seconds. When the Torque Proving function is enabled, the Float time is ignored at the end of the ramp. This feature can be used without enabling the Torque Proving function. Care must be taken that there is enough dynamic braking to insure that decelerating the total inertia of the system can be accomplished with this decel rate of 0.1 sec.

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