Sinamics S120 Regenerative Power: r0032, r0082, r0039 Reference

Regenerative energy recovery in a SINAMICS S120 drive system is not exposed as a single, dedicated display parameter the way active motor power is. Engineers have to select the correct r-parameter based on whether the point of interest is the infeed (Line Module / Smart Line Module / Active Line Module) or the Motor Module, and then interpret the sign of the value to distinguish motoring from regenerating operation. This reference consolidates the parameter set, smoothing behavior, firmware version availability, kWh calculation methodology, and commissioning verification steps for a 315 kW S120 chassis-class drive.

1. System Overview and Where Power Flows

The SINAMICS S120 is a modular drive system. Power is captured in two distinct places:

• Line Module (infeed) – Active Line Module (ALM), Smart Line Module (SLM), or Basic Line Module (BLM). It is the boundary where the line-side meets the DC link. Energy recovered from the motor flows back through the Motor Module into the DC link and then back into the line through the Line Module.
• Motor Module – the inverter stage that drives the motor. Motor-side power, including negative (regenerative) power, is measurable here directly.

Because these two measurement points are on opposite sides of the DC link, the parameter numbers, sign convention, and meaning of "regenerative" are not identical between them.

2. Active Power Parameters on the Motor Module

On the Motor Module, regenerative power is observed by looking at the sign of the active power actual value. The two relevant parameters are r0032 and r0082. They share the same unit (kW) and the same physical quantity, but they differ in smoothing.

3. Active Power Parameters on the Infeed (Line Module)

The infeed has a different parameter set. r0032 and r0082 still exist on the Line Module object, but they represent line-side active power, i.e. power flowing from the grid to the DC link. The sign convention is reversed compared to the Motor Module:

• Positive r0032 / r0082 on the Line Module: line is supplying power to the drive (motoring operation, or all line losses are positive).
• Negative r0032 / r0082 on the Line Module: line is receiving power from the drive (regenerative operation; only possible on an Active Line Module or Smart Line Module – a Basic Line Module cannot feed back).

r0039 is not the power unit utilization on an infeed object in the same way as on a Motor Module. On the Line Module it is typically the temperature/utilization model of the line-side IGBTs. The Motor Module's "power feedback" parameter (r0039 in newer firmware) does not exist on the infeed object.

4. Firmware Version Availability of r0039

r0039 as a feedback power parameter in the Motor Module Servo/Vector objects was introduced in firmware V4.5. Earlier firmware versions do not expose it on the Motor Module – it is only available on the Control Unit / Line Module in pre-V4.5 builds. Confirm the installed firmware before commissioning with this parameter:

1. Open STARTER or Startdrive and go online to the drive.
2. Read r0018 (firmware version) on the Control Unit.
3. Navigate to the Motor Module and read r0039 from the parameter list.
4. If r0039 is greyed out or returns 0 on a Motor Module, the firmware is older than V4.5 – use r0032 / r0082 instead.

5. kWh Calculation for Regenerative Energy Savings

To translate the regenerating power into an energy value (kWh), integrate r0082 over time and accumulate only the negative portion. The fundamental relation is:

E_regen [kWh] = (1 / 3 600 000) * sum( r0082 [W] * dt [ms] )   where r0082 < 0

Equivalently, in engineering units, if r0082 is sampled every cycle (p0115[0] typically 250 µs on a CU320-2, 1 ms on a CU310):

E_regen [kWh] = (1 / 3 600) * integral( r0082 [kW] * dt [s] ) over regeneration intervals only

Implementation Options

DCC Block Skeleton

A typical DCC implementation uses the following signal chain. All blocks are standard SINAMICS DCC library elements.

  r0082 (kW, unsmoothed)
    |---[NEG]---|---[INTG]---> r_accum (kW * ms, internal)
    |            |              |
    |            |          [MUL by p0115[0] / 3600000]
    |            |              |
    |            |          r_Eregen_kWh  --> r3998[0] (free parameter)
    |
    |---[ABS]--> zero suppression / enable logic
    |
  threshold r3999 (kW)  ---[GE]---> enables INTG only when r0082 < -r3999

Mapping the result to a free parameter (e.g. r3998) makes the value available on STARTER/Startdrive trace, on the AOP30 operator panel, and on an HMI via tag routing. Recommended scaling: 1.0 means 1 kWh per unit. If the integrator can overflow, choose a wrap strategy or use a 64-bit counter (available in DCC as ADD64 / MUL64).

6. Sampling, Smoothing, and Anti-Aliasing

Before reading r0032 for an energy-saving claim, configure p0045 (smoothing time constant of the active power display). Default values are usually 100 ms on a Vector object and 0–10 ms on a Servo object. For energy integration:

• Set p0045 = 0 if you want the raw value; use r0082 instead, which is never smoothed by p0045.
• Set p0045 = 50–200 ms if the value is being displayed on an HMI and you want a stable readout; this hides very short regen events.

For a hoist or test bench where a 0.5 s regenerating pulse must be captured, do not rely on r0032.

7. Reading Parameters from the HMI / TIA Portal

On a TIA Portal HMI (Comfort Panel, WinCC Unified, or WinCC Professional) connected via PROFINET to a SIMATIC S7 controller that is reading the drive via PROFIdrive, expose r0032 / r0082 through standard telegram 1, 2, 3, or 5. None of the standard telegrams include active power; you need a free telegram (e.g. telegram 999) with the PZD mapping configured in STARTER:

1. In STARTER, open the drive project and select Communication > Telegram configuration.
2. Choose a free telegram, e.g. 999.
3. Map r0032 or r0082 to a PZD word (16-bit integer, scaling 0x4000 = 100 % of p2000 reference).
4. In TIA Portal, add the drive to the device configuration and import the GSD.
5. Bind the configured PZD to an HMI tag.

Reference: SINAMICS S120 List Manual (LH1) entry for r0032 / r0082.

8. Verification Procedure

After commissioning the kWh accumulation, perform the following verification on the 315 kW drive:

1. Static check (no motion): read r0032 on the Motor Module with the drive enabled but at zero speed. Expect a value close to 0 kW (only iron losses and switching losses – typically 0.3–1.2 % of rated). If r0032 is far from zero, the current controller or DC link voltage measurement may be faulty.
2. Motoring check: run the motor at 50 % rated speed with 50 % rated torque. r0032 should be positive, equal to P_mech + losses (≈ 160 kW for a 315 kW motor at this operating point).
3. Regenerating check: with the drive in speed control, command a fast deceleration (e.g. from +1500 rpm to 0 rpm in 200 ms with a 1.5× rated torque limit). r0032 / r0082 should swing negative. Capture the trace and integrate.
4. Infeed cross-check: while regen is active, the Active Line Module r0032 should go negative. This is the externally visible "feeding back to the grid" value.
5. Counter cross-check: compare the DCC-accumulated kWh against a clamp-on power analyzer on the line side over a controlled regen cycle (e.g. 10 full decelerations of a known inertia). Disagreement > 5 % indicates either smoothing loss in r0032 or an integrator scaling error.

9. Common Pitfalls and Troubleshooting Matrix

10. Working Numerical Example (315 kW S120 with Hoist Load)

A 315 kW motor (p0307 = 315 000 W, p2000 = 1500 rpm) drives a hoist. The motor is at +1500 rpm, fully loaded with a stationary counterweight. The operator commands a controlled stop with p1121 = 4.0 s. The mechanical power at full speed:

P_mech = T * omega = 2006 Nm * (2*pi*1500/60) = 315 000 W (rated)

During deceleration, with the same torque limit:

P_regen [W] = T_load * omega(t) - T_brake * omega(t)   (signs: mechanical power out of motor, brake energy into motor)
            = (2006 - 0) Nm * omega(t)  for counterweight-driven descent (true regen, no active brake)

Energy returned to the line over 4 s, assuming constant omega ≈ 1500 rpm:

E = P * t = 315 kW * 4 s = 1260 kJ = 0.350 kWh per controlled stop

100 stops per shift (8 h), 2 shifts/day, 250 working days:

E_annual = 0.350 * 100 * 2 * 250 = 17 500 kWh / year

At an electricity price of 0.18 €/kWh, this is approximately 3 150 € / year of recovered energy. Use the DCC integrator on r0082 to confirm the figure in service. Add the I²R losses in the line reactor and DC link (typically 1.5–2 % of throughput) to get the net grid-side recovery.

11. Safety and Functional Notes

• For functional safety, the energy recovery path is independent of the STO (Safe Torque Off) input. STO removes the gate pulses on the Motor Module; regen flow stops. The Line Module can continue to operate.
• The Active Line Module's regenerative current limit is set by p1531 (current limit, regenerating) and p3531 (regenerative power limit, as a function of line voltage). On a 315 kW ALM, default p1531 is typically 100 % of rated.
• On Smart Line Module, the regenerative power limit depends on the line voltage tolerance. A 400 V SLM at 415 V line may have a higher available regen current than at 380 V – refer to the operating instructions for the variant.

12. Related Parameters Worth Knowing

For the full parameter set, the SINAMICS S120/S150 List Manual (LH1) remains the canonical reference. For commissioning with STARTER or Startdrive, see the S120 Getting Started and the Startdrive Commissioning Manual.