Troubleshooting of Siemens MASTER DRIVES VC

Siemens MASTER DRIVES VC Troubleshooting and Parameter Optimization Guide

Overview: SIMOVERT MASTER DRIVES Vector Control (VC)

SIMOVERT MASTER DRIVES is Siemens' classic drive platform, with its Vector Control (VC) version designed specifically for high-performance closed-loop control, supporting V/f characteristics, frequency control, speed control, and torque control. Its control unit CU (including parameterized unit PMU) provides rich digital/analog interfaces and serial communication, widely used in various industrial fields. For engineers responsible for maintaining old equipment, mastering its operating structure, parameter system, and fault diagnosis methods is the key to ensuring the continuous operation of the production line.

Preparation before startup: capacitor pre charging and first power on

2.1 Capacitor pre charging (Forming)

If the frequency converter is stored for more than a year without being powered on, the DC bus capacitor must be recharged. Users can check the production date on the nameplate (such as "H1994" indicating August 1994) to determine. The pre charging time depends on the storage duration (Figure 4.1): it takes about 30 minutes to store for 1 year, 60 minutes for 2 years, and 2 hours for 4 years or more.

There are two methods for pre charging:

AC-AC or DC-AC devices: Charge the DC bus through an external rectifier bridge and resistor (Figure 4.2/4.3), and the main power supply must be disconnected.

DC-AC unit: Slowly increase the DC bus voltage to the rated value.

The recommended pre charging components include SKD 50/12 rectifier bridge, 220W resistor, and 22nF capacitor (for 208V-415V systems).

2.2 First Start Basic Process

The frequency converter is pre-set with basic parameters (factory settings) when it leaves the factory, supporting 50Hz induction motor V/f open-loop operation. If this configuration meets the on-site requirements, it can be directly powered on for operation. Otherwise, parameterization is required according to the following path:

Standard application (V/f characteristics, no options): Suitable for simple applications such as fans and pumps.

Expert applications (closed-loop control, dataset switching, interface control): used in complex scenarios, including vector control, option boards, etc.

The core parameter for expert application is P052 (function selection), which can be entered into the corresponding debugging steps by setting different values:

P052 function

1. Restore factory settings

2 Initialization (input MLFB model)

4 Hardware Configuration (Option Board)

5 Drive settings (motor/frequency converter data)

6 Automatic parameterization

7. Motor recognition in static state

8 Complete motor identification (including rotation)

9. No load measurement

Optimization of 10 speed controllers

12 Speed measurement machine test

Key Tip: Before executing the "Driver Settings" (P052=5), it is necessary to set P051=3 (Expert Mode) to enable all parameters. After modifying the motor data, P052=6 or 7/8 must be executed, otherwise the control parameters will not match.

Detailed explanation of startup debugging steps

3.1 Hardware configuration (P052=4)

If there are option boards (CB communication board, TB technology board, SCB serial board, TSY speed/synchronization board), they need to be defined through P090 (slot 2) and P091 (slot 3). For example, insert the TSY board into slot 2: P090=4. Attention: The technical board must be inserted into slot 2 and cannot coexist with TSY.

3.2 Driver Settings (P052=5)

Enter nameplate data in this step:

P071: Input voltage of frequency converter (AC is the power supply voltage, DC is the DC bus voltage)

P072: Rated current

P101: Rated voltage of motor

P102: Rated current of motor

P107: Rated frequency of motor

P108: Rated speed of motor

P109: Polar logarithm (automatically calculated, corrected if necessary)

At the same time, P163 (control type) can be set:

0: V/f+speed closed-loop

1: V/f open-loop

2: Textile specific V/f

3: Frequency control (without encoder)

4: Speed control (requires encoder)

5: Torque control (requires encoder)

When exiting P052=5, you can choose to execute P052=6/7/8/11, or return directly (P052=0). If an F061 error occurs, it indicates that the parameter is out of range, and r949 displays the incorrect parameter number.

3.3 Automatic parameterization (P052=6)

Automatically calculate control parameters based on motor nameplate data, such as current loop gain P253/P254, excitation time P189, etc. This step only affects the current motor dataset.

3.4 Motor identification (stationary/rotating)

Static recognition (P052=7): includes ground fault testing, pulse testing, leakage inductance measurement, and DC current measurement. Warning: Current may flow through the motor and the rotor may rotate. The ON command must be given within 20 seconds after the alarm A078 appears, otherwise the timeout interrupt (F114) will occur.

Complete recognition (P052=8): Used for vector control mode (P163=3/4/5), sequentially performing static recognition, no-load measurement, and speed controller optimization. Before conducting rotational measurements, it is necessary to set the maximum frequency (P452/P453) and torque limit (P492/P498) to prevent damage to the load.

Speed controller optimization (P052=10): Automatically measure mechanical inertia, set P225 (Kp), P229 (Tn), and P243 (feedforward). The optimization quality depends on P346 (expected dynamic factor, 10-200%). If F006 (DC bus overvoltage) occurs during the optimization period, the regenerative power limit P233 can be reduced (set to -3%~-0.1%).

3.5 Speed measurement machine test (P052=12)

Used to check the wiring and parameters of pulse encoders or analog speedometers. If the encoder pulse count P209 or the analog speedometer calibration P210 is incorrect, fault F051 or F098 will be displayed.

Common fault codes and countermeasures

4.1 Overvoltage fault F006

Reason: The DC bus voltage exceeds the trip threshold (e.g. 380V system>819V). Commonly seen in regenerative loads or excessive deceleration.

Countermeasure:

Increase deceleration time P464

Activate Vdmax controller (P377=1, P378=50%)

If using a regeneration feedback unit, check its configuration

For parallel inverters, r949=1/2 indicates overvoltage in the master/slave rack

4.2 Under voltage fault F008

Reason: The DC bus voltage is below 76% of the rated value (61% when the kinetic energy buffer is activated). It may be caused by power grid transients or rectifier failures.

Countermeasure:

Check if the input voltage matches P071

Check the incoming contactor and fuse

If using kinetic energy buffer (P379=1), ensure that the motor inertia is sufficient and the speed is not lower than 10% of the rated frequency

4.3 Overcurrent fault F011

Reason: Output short circuit, ground fault, or motor overload.

Countermeasure:

Check the motor cable and motor insulation

Check if the motor is stuck

Confirm that the frequency converter matches the motor capacity

Check if the dynamic requirements are too high (such as acceleration time being too short)

4.4 Motor stalling fault F015

Reason: Motor stalling or excessive load mutation, with a duration exceeding P520.

Countermeasure:

Reduce the load and release the brake

Increase current limit P173

Increase P520 (stalling time)

For frequency control (P163=3): increase low-frequency current P202/P203, or accelerate EMF model switching frequency P284

4.5 External faults F035/F036

Reason: Low level (fault signal) detected through binary input configured with parameters P575/P586.

Countermeasure: Check the peripheral devices and wiring, or modify the parameter values (such as setting 1 to indicate normally closed contacts).

4.6 Encoder fault F051

Reason: Missing signal from the speedometer, incorrect polarity, and incorrect pulse count setting.

Countermeasure:

Check the encoder wiring and shielding

Verify that P209 (pulse count) matches the encoder nameplate

For the analog speedometer, calibrate P210 (speed corresponding to 10V)

Key software function configuration

5.1 Automatic restart (WEA, P366)

Used for automatic recovery after power grid sudden shutdown. Parameter options:

P366=1: Only clear the fault, do not automatically restart

P366=2: Automatic restart after P367 delay (the ON command still exists)

P366=3: Always restart with "restart tracking" function

Security Warning: Automatic restart may cause unexpected startup and must be enabled only after the application evaluates security risks.

5.2 Kinetic Energy Buffer (KIP, P379=1)

Utilize load inertia to maintain DC bus voltage during short-term power outages. When the DC voltage is lower than the set value of P380, the controller reduces the frequency to maintain the loss, and then increases the ramp after the voltage is restored. Suitable for high inertia loads such as fans and flywheels.

5.3 Flexible response (FLR, P379=2 or 3)

Allow the frequency converter to output partial power even when the voltage drops to 50% of the rated value. requirements

External 24V power supply (X9 terminal)

Incoming reactor (4%)

The main contactor shall not disconnect when the voltage drops

5.4 Vdmax controller (P377=1)

Inhibit regeneration overvoltage. When the DC voltage rises, the controller increases the output frequency to put the motor into a generating state, thereby limiting the voltage. For systems without brake choppers, this function is crucial. If alarm A041 appears, it indicates that the grid voltage is too high or P071 is set too low.

5.5 DC braking (P372=1)

Triggered by the OFF3 command, apply a direct current (P373) to brake below the set frequency (P375) for a braking time of P374. Only applicable to asynchronous motors, pay attention to motor heating.

5.6 Flying Restart (P583)

Used for inputting frequency converters into rotating motors to avoid overcurrent. When there is no encoder, the scanning method is used (search current P369, search speed P370), and when there is an encoder, it is directly synchronized. If P366=3, restart tracking will be performed every time power is turned on.

Standardization of analog input/output

6.1 Analog Input (AE) Configuration

P650: Define input types (0: ± 10V, 1: 0-10V/0-20mA, 2: 4-20mA). When set to 2,<2mA triggers disconnection fault F037.

P651: Filtering time (4-1000ms)

P652: Zero offset (± 20V range)

Application example: The main input comes from AI1 (0-10V corresponds to 0-50Hz).

Set P443.1=1003 (AE1), P650.1=1, P444.1=70% (gain), P445.1=30% (offset), which can map the range of 15-50Hz.

6.2 Analog Output (AA)

P655: Select the output parameter number (such as r004 output current, r218 frequency actual value)

P656: Gain (voltage value at 100% corresponding to 10V)

P657: Offset

Calculation example: 0-10V corresponds to 32-160A (rated current 40A).

Reference quantity 4 × P102=160A. According to the formula P656.2=12.5V, P657.2=-2.5V.

Interpretation of Control Words and Status Words

7.1 Control Word 1 (r550)

Key position:

Bit 0: ON/OFF 1 (rising edge start)

Position 1: OFF2 (pulse lock, free parking)

Position 2: OFF3 (Quick Stop)

Position 3: Inverter Enable

Bit 7: Fault reset (edge triggered)

Position 11/12: Forward and Reverse

Position 13/14: Electric potentiometer up/down

All command sources can be freely connected through parameters (such as P554 selecting ON/OFF 1 source, default PMU button).

7.2 Status Word 1 (r552)

Important information:

Position 0: Ready to power on

Position 1: Ready

Position 2: Running

Bit 3: Fault (Low level output indicates' faulty ')

Position 12: The main contactor has been engaged

Position 13: Slope generator activation

The status bit can be assigned to digital output (such as P603.1=1002 outputting "fault" to BA2).

Common alarm codes and their handling

Alarm meaning countermeasures

A020 overcurrent check load, reduce ramp time

A022 Inverter Overheating Inspection: Fan, Environmental Temperature, and Heat Dissipation

A025 I ² t frequency converter reduces load or increases pulse frequency

A029 I ² t motor inspection motor cooling, increase P363

A033 overspeed increases P452/P453 or reduces regeneration load

A034 set/actual deviation too large check torque limit, increase P517

A041 Vdmax controller prohibits checking input voltage and P071

A078 Static measurement to be executed with ON command given within 20 seconds

Maintenance and fault records

The frequency converter has built-in fault records (r947, r949), which can store up to 8 trip times (r748) and fault values. It is recommended that engineering personnel regularly export and fill in the logbook provided with the equipment. When replacing the CU board, it is necessary to initialize with P052=2 and input the correct MLFB (P070), otherwise the power unit cannot be matched.