Siemens Masterdrive MC Plus: Replacing 1FK6 with 1FK7 Servo Motor

Siemens Masterdrive MC Plus: Replacing a 1FK6 Servo Motor with a 1FK7 Servo Motor

The Siemens SIMOVERT Masterdrives MC Plus (unit series 6SE70, compact unit 6SE7013-0EP50) accepts a wide range of three-phase synchronous servomotors from the 1FK6 and 1FK7 families. When a legacy 1FK6 motor is replaced with a 1FK7 compact motor of the same shaft height, the drive must be re-parameterized for the new motor type code, equivalent-circuit data block, and resolver offset. This article documents the complete parameter migration path, the correct motor-data identification sequence, and the root-cause analysis of fault F114 that frequently appears during the swap.

1. Drive and Motor Identification

Before any parameter change, record the existing drive and motor identity so the swap can be rolled back if commissioning fails.

The 1FK6 and 1FK7 series share the same resolver feedback concept and the same SINECOD encoder protocol on incremental resolvers with two pole pairs. The compact 1FK7 differs mainly in higher torque density, lower rotor inertia, and a different terminal box layout. The drive automatically handles the resolver pole-pair count when the motor type code is loaded, but only if the correct code is written to P96 first.

2. Prerequisites

1. Confirm the unit version of the 6SE7013-0EP50. The 1FK7 motor list was added to the Masterdrive firmware in version 3.20. Versions older than 3.20 reject unknown motor codes and raise F114 immediately after the ON command.
2. Back up the current parameter set with DriveMonitor, SIMOVIS, or the OP1S operator panel (Upload to OP / Upload to PC).
3. Read and record the rating plate of the new 1FK7042-5AF71-1TA0 motor: rated speed n_n, rated torque M_n, rated current I_n, EMF constant k_E, torque constant k_T, rotor moment of inertia J, and the resolver pole-pair number.
4. Verify the motor holding brake wiring (terminals BD1 / BD2 on the resolver / power connector). 1FK7 brakes are 24 V DC, polarity protected.
5. Check resolver cable shield bonding at the drive end; 1FK7 motors are more sensitive to resolver-signal distortion than 1FK6 due to higher resolver bandwidth.

3. Step-by-Step Motor Replacement Procedure

3.1 Mechanical Installation

1. Isolate the drive, lock out / tag out the line, and wait for DC-bus discharge.
2. Remove the 1FK6042 motor and mount the 1FK7042 on the same flange and shaft coupling. Shaft height 60 mm is identical between the two motor series, so adapter plates are normally not required.
3. Connect the power cable U / V / W to the drive output terminals. Verify phase sequence; reversed phases cause the motor to run with a 60° resolver offset and will fail motor identification.
4. Connect the resolver cable to X103 (Resolver) on the Masterdrive. Pin assignment is pin 1 = R1 (ref +), pin 2 = R2 (ref -), pin 3 = S1 (cos +), pin 4 = S3 (cos -), pin 5 = S2 (sin +), pin 6 = S4 (sin -).

3.2 Parameterization of Motor Type (P96)

On the PMU (7-segment display) or OP1S, navigate to parameter P96 and enter the new motor type code.

P96 = 163   ; 1FK7042-5AF71-1TA0
P96 (old) = 3 ; 1FK6042-6AF71-1TA0

The drive stores the motor type code in non-volatile memory. After writing P96, the drive reloads internal motor defaults, including:

• Number of pole pairs (P111)
• Resolver offset (P121, P122)
• Current limits (P128, P129)
• Speed limits (P114, P115 in n_set)

Do not skip the next step — P101 - P109 override the internal defaults and must reflect the actual rating plate of the new motor.

3.3 Equivalent-Circuit Data Block (P101 - P109)

Enter the following parameters from the 1FK7042-5AF71-1TA0 rating plate. Values shown are typical for a 60 mm shaft height, 8-pole 1FK7; verify each value against the motor's nameplate.

3.4 Trigger Motor Data Identification (P115 = 2)

The Masterdrive performs an automatic measurement of stator resistance, leakage inductance, and resolver offset when P115 is set to the identification mode and the drive is given an ON command within 20 seconds.

1. Set P115 = 2 (rotating identification with shaft movement up to one mechanical revolution).
2. Set P115 to 1 for a static (no rotation) identification if the motor is mechanically locked or coupled to a load that cannot rotate freely.
3. Within 20 seconds, issue the ON command (terminal 5, OP1S, or bus control word bit 0).
4. The drive accelerates the motor briefly, measures equivalent-circuit parameters, writes the results back to P106 / P107 / P121 / P122, and clears P115 automatically to 0.

4. F114 Fault: Root Cause Analysis and Resolution

F114 on the 6SE7013-0EP50 has multiple root causes that all map to the same fault number. The diagnosis matrix below is built from field experience and from the Siemens Masterdrive Compendium fault list.

4.1 Resetting the F114 Fault

P398 = 0     ; clear fault buffer
P398 = 1     ; acknowledge fault
; Wait until r047 = 0 before re-triggering identification

Some firmware versions require a power-cycle of the control card (CUMC) after acknowledging an F114 to re-initialize the resolver tracking loop. With the unit version written in the drive label, verify against the firmware release notes whether a power-cycle is mandatory.

5. Resolver and Encoder Considerations

1FK6 motors with a 6AF71 resolver and 1FK7 motors with a 5AF71 resolver both use a two-pole-pair brushless resolver. The Masterdrive X103 input is universal across both series. The resolver offset (P121 / P122) must be re-measured, not transferred from the old motor. The P115 = 2 procedure performs this measurement automatically and writes the result to P121 / P122.

If the resolver was changed mechanically (e.g. a replacement motor shipped from stock has a different resolver supplier), the offset may be more than 30° off and the rotating identification must complete a full electrical cycle. In some cases the drive requires P115 = 4 (extended identification with multiple rotations) to settle the offset. P115 = 4 is only available on firmware >= 3.30.

6. Drive Retuning After Motor Swap

Once motor identification completes and the fault buffer is clear, the speed and current controllers must be re-tuned because the rotor inertia and torque constant differ between the 1FK6 and 1FK7 series.

1. Speed controller optimization: P236 = 1 to start the auto-tuning routine. The drive applies step changes to the speed setpoint and measures the response.
2. Current controller optimization: P235 = 1 for the field-oriented current controller adaptation.
3. Save the new parameter set to the non-volatile memory of the CUMC board (P971 = 1 to copy RAM to EEPROM).
4. Record the new tuning results in r150 - r158 for the maintenance log.

7. Commissioning Verification

8. Troubleshooting Matrix for Recurring Issues

9. Field-Proven Caveats

• After firmware upload, P96 must always be re-validated. Some versions of the Masterdrive parameter loader reset P96 to 0 if the stored motor type is not present in the new firmware's motor list.
• If the 1FK7042 motor is a self-cooled (non-fan) variant, the rated current P102 must be reduced by approximately 15 % versus the fan-cooled rating plate to avoid thermal trip.
• When the 1FK7 motor is paired with a planetary gearbox, set P215 (gear ratio) and P216 (gearbox efficiency) before the speed controller optimization, otherwise the auto-tuning will produce a too-aggressive Kp_n.
• Spare CUMC boards shipped as replacements ship with factory default P96 = 0. The motor swap procedure must be re-run end-to-end after a CUMC swap, not just the controller tuning.

10. Related Parameters Not to Forget

11. Summary Workflow Diagram

FAQ