MM440 Motor Overload Trip Not Working: F0001 Configuration Guide

Problem Summary

A 2.2 kW Siemens MICROMASTER 440 (MM440) inverter is being used to drive a 1.5 kW pocket feeder motor. The motor nameplate has been entered (P0305 = 3.5 A), the motor overload factor (P0640) has been reduced from 150 % to 100 %, the motor I²t temperature reaction (P0610) is set to 2, and the inverter overload reaction (P0290) is set to 1. Under sustained full-load operation the drive only generates warning A0501 (current limit reached) but never raises the overload fault F0001, so the trip relay on digital output 1 (P0731 = 52.3) does not de-energise. The same relay does trip correctly during an analogue wire-break (F0080), which proves the output hardware, the BICO routing, and the trip coil wiring are healthy. The fault is therefore a configuration gap in the MM440 protection chain, not a hardware failure.

This article explains the MM440 motor thermal model, walks through every parameter that contributes to an overload trip, and provides three field-proven strategies that recover the F0001 trip path or replace it with a deterministic, time-limited trip on a free-function block. It also documents the A0501, F0001, F0004, F0011, F0080, and F0085 fault/alarm codes so an engineer can read the drive status word and confirm the trip path in service.

MM440 Motor Overload Protection Architecture

The MM440 stacks three independent protection layers, and each has its own parameter block, trip reaction, and fault number. The motor protection layer uses an I²t model computed from the measured stator current and the nameplate data; the inverter protection layer uses an I²t model of the IGBT thermal mass; the hardware layer is a single-cycle IGBT desaturation comparator that triggers on a real short-circuit event. A load above rated current will typically fire the motor I²t trip (F0011) before the inverter I²t trip (F0004), and the hardware trip (F0001) only on a true short or ramp-up inrush above the IGBT desaturation threshold.

Layer 1 - Hardware overcurrent (F0001)

F0001 is latched by the gate-driver desaturation comparator. It is not a thermal model. Typical trigger currents are 200-300 % of drive rated output current and the reaction time is one PWM cycle. If the application wants a "trip" on motor overload, F0001 is the wrong fault to use - the engineer is configuring software that the hardware can never satisfy. The correct motor thermal fault is F0011, generated by Layer 2.

Layer 2 - Motor I²t thermal model (F0011)

Layer 2 integrates (I_actual / P0305)² over time, normalised against P0640 and P0611. The output is the motor thermal utilisation r0034. P0610 selects the reaction when r0034 reaches 100 %:

Set to 2, the drive should warn at 100 % utilisation and trip on F0011. If the drive warns but never trips, the most common cause is that the warning is configured but the trip threshold is being masked, or the thermal model is being reset by a Stop / RESTART before it has integrated long enough to latch.

Layer 3 - Inverter I²t thermal model (F0004)

Layer 3 protects the IGBT module. Triggered by heatsink temperature (r0037) and an internal IGBT junction I²t integration. Reaction is set in P0290:

Root Cause Analysis: Why F0001 Stays Clear

The reported configuration is:

• P0640 = 100 % (motor overload factor)
• P0610 = 2 (warn at 100 %, trip F0011 at 100 %)
• P0290 = 1 (trip F0004 on inverter overload)
• P0731 = 52.3 (relay 1 = "drive tripped" status word bit)

Three reasons explain the symptom:

1. F0001 is not the motor I²t fault. The drive cannot ever generate F0001 from a 100 % overload. F0001 is the hardware overcurrent fault. The motor thermal trip is F0011, and the user is not seeing F0011 either, which means the I²t warning is firing but the trip latch is not engaging - usually because the motor is not actually sustaining 100 % utilisation long enough to cross the trip integration threshold, or because the motor current being measured is below the expected 3.5 A.
2. A0501 is the wrong alarm to watch. A0501 is "current limit reached" (r0053.6 / r0053.3 depending on firmware) - it is generated by the current controller, not by the I²t thermal model. A0501 fires whenever the drive is at I_max clamp, which happens for a fraction of a second on each load step. A continuous A0501 with no F0001 / F0011 just means the drive is in current limit and is regulating speed - it is not a thermal protection event.
3. Drive derating in current limit. In a 2.2 kW drive with a 1.5 kW motor, the inverter can deliver up to ~150 % of drive rated current. P0640 = 100 % is interpreted as "motor overload current limit = P0305 × 100 % = 3.5 A". Because the drive can comfortably supply 3.5 A, the I²t integrator rises very slowly; at the same time P0290 = 1 means inverter I²t also needs to be at 100 % to trip, and the inverter is nowhere near its thermal limit. The result is a warning that never crosses into a fault because the protection system was never the limiting element - the load is.

Affected Parameters Reference

Alarm and Fault Code Map

Strategy A - Restore I²t Trip with P0610 = 1 or 2

The simplest, most standards-compliant fix is to let the MM440's built-in I²t model do the job. The drive's I²t integrator accumulates (I / P0305)² over time, normalised by P0611. Trip is dispatched at r0034 = 100 % per P0610. For a 1.5 kW motor on a 2.2 kW drive, the right configuration is:

1. P0305 = motor nameplate full-load current (3.5 A in this case)
2. P0640 = 150 % (default, allows 1 min 50 % overload every 5 min for a Class B motor)
3. P0610 = 2 (warn at 100 %, trip F0011)
4. P0611 = 100 s (typical for 4-pole TEFC motor up to 7.5 kW; refer to motor data sheet)

If the customer needs a tighter trip, reduce P0611. The trip time at overload current I is approximately:

t_trip = P0611 / ((I / P0305)² × (P0640/100)² - 1) [s]

For P0611 = 100 s, P0305 = 3.5 A, P0640 = 150 %, an overload of 4.0 A (114 % of rated, or 76 % of overload factor) yields:

t_trip = 100 / ((4.0/3.5)² × 1.5² - 1) = 100 / (1.307 × 2.25 - 1) = 100 / 1.94 ≈ 51.5 s

For a tighter 4 s trip on a 4.0 A overload, set P0611 = 4 s. Note that reducing P0611 below the motor's real thermal time constant makes the protection conservative; verify against the motor's locked-rotor withstand time from the manufacturer datasheet.

Strategy B - Programmable Threshold Trip Using P2170 / P2171 and Free Function Blocks

If the customer wants a deterministic, time-limited trip that the operator can adjust from the keypad, the cleanest implementation is the MM440's programmable current threshold:

• P2170 = current threshold expressed in % of P0305 (e.g. 100 = 3.5 A)
• P2171 = time the current must exceed the threshold before the trip fires

The threshold-exceeded flag is available in the status word r0053. The recommended path is to connect r0053.3 (or r0053.6 in older firmware) to the external fault input P2104 via a free function block (FFB) configured to invert the signal, so the drive trips with F0085 (external fault) when the threshold is held longer than P2171.

Step-by-step procedure

1. Set P0700 = 2 (default - terminals) or 1 (BOP) so the BICO is not locked.
2. Set P2170 = 100 (= 100 % of P0305, i.e. 3.5 A for this motor).
3. Set P2171 = 4 s (or the value dictated by the customer).
4. Open the free-function block set (P2800 = 1 to enable; P2801 = 6 to enable the first comparator; P2802[0] = 6 to enable the first NOT gate).
5. Wire the threshold flag (r0053.3 or the connector signal assigned to "I > P2170") to the input of a NOT block.
6. Connect the output of the NOT block to P2104 (external fault 1 source).
7. Set P2100 = 0 (use F0085).
8. Set P2101 = 1 (OFF2 coast stop on the external fault - matches the wire-break behaviour of F0080).

FFB truth table (simplified)

Strategy C - Inverter Overtemperature Trip via P0290

The reported setting P0290 = 1 means the drive will trip on F0004 if the inverter IGBT thermal model saturates. On a 2.2 kW drive feeding a 1.5 kW motor, the inverter will not reach F0004 under normal overload - the inverter is sized 47 % above the motor. P0290 = 1 is therefore the wrong protection layer for this application. If the customer insists on an inverter-level trip, leave P0290 = 1 but pair it with P0292 = 50 % to fire A0504 earlier, and combine it with P2170 / P2171 for the deterministic trip. Do not rely on P0290 alone for motor overload detection on a right-sized drive.

Trip Output Relay Wiring and Status Word Verification

With P0731 = 52.3, digital output 1 (terminals 19-20 on the control board) closes when r0052.3 (drive tripped) is high. r0052.3 follows the OR of all active faults that are not masked by P2100 / P2101, so it will activate on F0001, F0011, F0004, F0080, and F0085 equally. If the relay does not change state on F0080 but does change state on F0085, the FFB wiring in Strategy B is wrong. If it does not change state on F0080 either, the BICO link P0731 = 52.3 is broken or the relay is wired to the normally-open contact incorrectly.

Relay wiring summary

Commissioning, Verification, and Parameter Save

1. Enter motor nameplate: P0304 = rated voltage, P0305 = rated current (3.5 A), P0307 = rated power (1.5 kW), P0310 = rated frequency (50 Hz), P0311 = rated speed (e.g. 1410 rpm).
2. Apply Strategy A first (cleanest): set P0640 = 150, P0610 = 2, P0611 = 100. Run the motor to 100 % load and confirm that A0511 appears within 60-90 s and F0011 appears shortly after. If F0011 fires, the task is done.
3. If the customer requires a deterministic, keypad-adjustable trip time, apply Strategy B in addition: set P2170 = 100, P2171 = 4, enable the FFBs, and wire r0053.3 → NOT → P2104.
4. Forcibly run the motor at 110 % load using a load bank or a controlled overload. Verify A0501 fires within 1 s, A0511 fires within 60 s, and F0011 / F0085 trips within P2171 + I²t time.
5. Confirm the trip relay de-energises (terminals 19-20 open) on every fault class (F0001, F0004, F0011, F0080, F0085) by reading r0052.3 on the BOP (parameter r0000 = drive status display, "tripped" indicator).
6. Save parameters to EEPROM with P0971 = 1 (wait for the BUSY message to clear before power-down).
7. Document the as-saved parameter set on the drive's parameter sticker so the next shift engineer can reproduce the configuration after a factory reset.

Troubleshooting Matrix

Frequently Asked Questions