Sizing Power and DRIVE-CLiQ Cables for the Siemens 1PH4168

Overview

The Siemens 1PH4168-4QF26 is a member of the 1PH4 series of AC induction motors designed for machine-tool main-spindle and high-dynamic servo applications. When paired with a SINAMICS S120 Booksize Motor Module (for example, 6SL3121-1TE31-3AA3 at 132 A line current or 6SL3121-1TE24-5AA3 at 45 A) and a SINUMERIK 840D sl controller, the motor becomes a fully-digitised drive train with DRIVE-CLiQ as the encoder and data-bus backbone.

This reference describes how to select the two completely different cable categories required:

1. Power cable (U2/V2/W2/PE, motor feeder); sizing depends on the actual phase current required by the application, not the motor's catalogue-rated current.
2. Signal cable (DRIVE-CLiQ, dual-shielded twisted pair with green/orange conductors in the Siemens MOTION-CONNECT cable family). A Signal Module Interface (SMI) is only needed when retrofitting an existing non-DRIVE-CLiQ encoder; an IN22DQ-style encoder is already DRIVE-CLiQ native.

Because the original application is a low-load test bench that runs to maximum speed only momentarily, the cables are dimensioned against a derated current rating rather than the motor's full-load current. The drive itself can be undersized in current relative to the motor only when the operating point stays inside the S6/S2 envelope and the configuration in the SINUMERIK commissioning tools is set accordingly.

Motor and Drive Identification

1PH4168-4QF26 Article Code

The Siemens 1PH4 article-number convention follows a fixed pattern. The base type 1PH4168 identifies shaft height 160 and stack length 80. The suffixes describe the electrical and mechanical variant:

DRIVE-CLiQ Encoder IN22DQ D25

The encoder indicated on the operator's motor label is an IN22DQ equivalent (sometimes printed 1XP8001-1/A2C173846J family). It is:

• A multi-turn absolute encoder (counts position across power-off transitions).
• Wired through a 24-bit singleturn + 12-bit multiturn resolution over DRIVE-CLiQ.
• Powered only through the DRIVE-CLiQ interface (24 V supplied by the Module); no separate encoder supply cable is needed.

Because the encoder is DRIVE-CLiQ-native and absolute, no Signal Module Interface (SMI) sits between the motor and the SINAMICS Motor Module. The SMI is only required when the original motor has an incremental encoder (such as 1XP8001 with sin/cos) or a third-party resolver, and an SMI20/SMI24 module is inserted for translation.

SINAMICS Booksize Motor Module Options

Both can be controlled by SINUMERIK 840D sl over DRIVE-CLiQ when configured as the appropriate CompactFlash topology. In STARTER or the SINUMERIK commissioning tool (SVC), the active components are identified by the part of the article number printed on the label:

1. Active Line Module (for example 6SL3130-6AE21-0AB1) supplies the DC link.
2. The selected Motor Module is inserted on the DC link and exposes its DRIVE-CLiQ port(s) to the controller.
3. The motor's IN22DQ encoder occupies the next DRIVE-CLiQ node.
4. Any additional axis (LA / LB / LIC / ONC) ports required by I/O are populated with Terminal Modules (TMx) or Sensor Modules.

Why the Power Cable Can be Smaller for Test-Bench Duty

Conductor cross-section in AC motor feeders is governed by continuous current, not by maximum mechanical speed. The relevant sizing formula for a three-phase installation is:

I_n (A) = P_mech (W) / (sqrt(3) · V_LL · cosφ · eta)

Where:

• P_mech = mechanical shaft power required at the operating point (W)
• V_LL = line-to-line RMS voltage (V)
• cosφ = power factor at that operating point (typical 0.7–0.85 for spindle motors at low load)
• eta = motor efficiency (typical 0.90–0.95 for 1PH4 class)

If the test bench only spins the motor at no-load or low-load (no torque from the spindle), the actual RMS phase current is dramatically lower than the rated value printed on the rating plate. Two practical examples for a 1PH4168 motor on a 400 V three-phase supply:

Power Cable Selection

Cable Family

Siemens recommends the MOTION-CONNECT 800PLUS shielded feeder cable family (ordered under 6FX5008-1BBxx-Fxxx for fixed installation or 6FX8002-5xx cross-section series). Symmetric 3-core constructions with concentric shield + drain wire are mandatory for compliance with EMC directive and SINAMICS S120 emission specifications:

• Minimum insulation class: PVC or better (XLPE for higher ambient).
• Shield: tinned copper braid, optical coverage ≥ 85% (Siemens supplies ≥ 90%).
• Outer jacket: 9YY-style PVC, oil-resistant 11Y for machine tools.
• Symmetric, not 4-core; one PE conductor only.

For a fixed test-bench installation a 4-core cable is acceptable as an alternative, but symmetric 3-core is preferred because reduced common-mode current improves bearing-lifetime at high switching frequencies typical of SINAMICS drives. The same Siemens guidance applies: “Twisted or three-core cables with additional ground conductor should be used as motor feeder cables. The insulation should be removed from the ...” Siemens AC Induction Motors 1PH4 PDF.

Cross-Section Sizing

With the calculated operating current from the previous section, the copper cross-section can be downscaled relative to the catalogue-rated sizing. As a quick rules-of-thumb for a 600V-class PVC cable routed on open trays:

Per the Siemens 1PH4 manual, apply an additional 20% derating factor when:

• cable is bundled with other live cores in a raceway
• ambient > 40°C
• free length in air > 20 m bundled

Voltage Class

For a 1PH4168 running on a 400 V/480 V three-phase SINAMICS supply, use 600 V-rated cable minimum, 1000 V-rated cable preferred (typical Siemens 1PH4 cable designation: 0.6/1 kV). At higher DC-link voltages (8 kV class on large drives) confirm the cable is rated for the inverter peak dU/dt if they are outside the typical cabinets.

Connector Layout

Each 1PH4 motor variant is delivered with a defined power and signal connector arrangement:

• Power: terminal box with gland entries; ring lugs for U2/V2/W2/PE on M6/M8 studs. Torque per Siemens motor manual (commonly 4 Nm for power leads, 4–5 Nm for PE stud depending on stud size).
• Signal: M17 DRIVE-CLiQ circular connector (6-pin) on the motor housing. Pinout is proprietary; do not wire DRIVE-CLiQ as crimp-style Ethernet.

Signal Cable Selection (DRIVE-CLiQ)

Two Cable Generations

Absolute Signal Support

• Absolute-signal DRIVE-CLiQ: The cable carries the multi-turn position data (12-bit revolution counter). After the controller is switched on, the SINUMERIK reads the absolute position over DRIVE-CLiQ within < 1 second and can home the axes without a referencing run. Required when the motor uses an absolute encoder such as IN22DQ.
• Non-absolute DRIVE-CLiQ: Sometimes referred to on machines where an incremental encoder (sin/cos or TTL) is fitted with a separate SMI20 / SMI24. In this case the SMI module is the DRIVE-CLiQ node and reports position to the controller but does not carry absolute revolution data unless the encoder itself is absolute.

The IN22DQ encoder used here is absolute, so the following conditions apply:

1. Use a Siemens DRIVE-CLiQ cable with M17 plug at the motor end and RJ45 at the cabinet end. Standard 6FX5002-2CG00 series is correct.
2. Connect the other end to the matching Sensor Module port on the SINAMICS Motor Module or directly to the X200-class DRIVE-CLiQ input of the Motor Module (no SMI needed).
3. Configure the axis in STARTER / SVC so that the encoder appears as the EXTERNAL ENCODER for the position controller, not just as a speed feedback channel.

Pinout Reminder (Motor M17 Connector)

Twisting and pair assignment are part of the Siemens cable specification — do not splice a longer run with off-the-shelf RJ45 patch cord, because the shield and pair attenuation will exceed the 100 m / 100 MHz budget.

Topology and Cable Run Lengths

The recommended topology for the test bench is a star from the NCU through the Line Module and on to the Motor Module. The DRIVE-CLiQ cable from the motor's M17 plug terminates into the X202 port of the Motor Module reserved for direct encoder without Sensor Module, or routed via an intermediate Sensor Module if the cabinet layout requires separation.

Optional: Using the Smaller 45 A Motor Module

The 6SL3121-1TE24-5AA3 can drive a 1PH4168 motor provided the actual thermal loading stays within the I²t envelope of the module. Activate the following parameters during commissioning:

• p340 = i2t integration model enable (default) — leave at the default if available
• p640 = Current limit (set to 45 A)
• p1299 = Motor model enabling (configure the correct motor in p2900xx ID list)

The matching motor identification code for 1PH4168 is part of the SINUMERIK standard list (1PH416x-Fxxx entries). If a more recent SINUMERIK kernel releases an updated motor ID, use the updated value to ensure the field-weakening and thermal model match the actual stator winding.

Commissioning Steps

1. Identify the motor rating plate and verify article code, rated current, rated voltage, encoder code (should be IN22DQ or compatible). Cross-check against the SINUMERIK motor-ID list before powering up.
2. Configure the SINUMERIK in SVC with the project, insert the Line Module and Motor Module with the correct article numbers.
3. Perform drive commissioning: connect via STARTER / SVC, identify the actual topology, run “automatic” commissioning with motor identification at standstill and rotating measurement.
4. Connect power and encoder cables using the appropriate cross-section and DRIVE-CLiQ part numbers from the tables above. Both cable shields must be applied 360° on the EMC glands.
5. Verify DRIVE-CLiQ network: a green LED on each DRIVE-CLiQ port means the node is recognised and the cable is good. Yellow LED or off indicates wiring error or cable mismatch.
6. Test the absolute position: power off, move motor a fraction of a turn by hand, power back on. The SINUMERIK should report an absolute position that reflects the movement. If it returns to its previous reference position absolute position was lost — check IN22DQ cable and connector.
7. Run-up profile: start at a low speed, ramp to maximum speed, monitor thermal model (Motor temperature via KTY/PTC). For test-bench duty with no workpiece a high-speed pass for ~30 s is usually sufficient.

Verification Checklist

Fault Behaviour and Common Diagnostics

Notes