ELAU PacDrive SM Servo Motor Application and Maintenance Guide

The SM motor connects power, brake/temperature feedback, and encoder signals through three independent connectors (X2, X3, X4). Incorrect wiring can not only cause motor damage, but also lead to serious EMC issues.

1. Power connection (X2)

Pin definitions: U (1), V (2), W (3), PE (4). For high-power models in the SM 140 series (such as 290 and 370), the X2 connector is a screw terminal that can accommodate up to 4 mm ² cables.

Important reminder: For long-distance power cables, voltage drop and leakage current must be considered. The manual specifically states that when using long cables, the holding brake of the motor may require separate power supply or increased power supply voltage to ensure that the rated voltage (24V ± 10%) is obtained at the connection box.

2. Brake and temperature monitoring (X3)

Pin definition: Pin 1/2 is PTC thermistor (CPTC, switching temperature 130 ° C), pin 3/4 is brake (3: DC 0V, 4: DC 24V).

Key parameters of the brake:

SM 070: Holding torque of 2.5 Nm, rated power of 12W

SM 100: Holding torque 11 Nm, rated power 16W

SM 140: Holding torque of 22 Nm, rated power of 18W

Correct use of brake: Keep the brake only used to lock the shaft in a stationary state or when power is off, and strictly prohibit its use for deceleration or parking during normal operation. The energy absorbed by the brake during emergency stop (EM STOP) must be limited:

SM 070: Energy absorption ≤ 50 Ws per emergency stop

SM 100: ≤ 200 Ws

SM 140: ≤ 400 Ws

At least 3 minutes of cooling is required between two emergency stops, and the brake is allowed to make no more than 2000 emergency stops throughout its entire lifespan. Exceeding these limits can lead to premature wear or burning of brake pads.

3. Encoder connection (X4)

SinCos encoder: supports 1 Vpp sine/cosine differential signal, with 1024 signal cycles per revolution. By subdividing, extremely high resolution can be obtained. Pin definitions: 1 (U_S, 7-12V), 2 (GND), 3 (REFSIN), 4 (SIN), 5 (REF COS), 6 (COS), 7 (RS485-), 8 (RS485+). High quality shielded twisted pair cables must be used, and the shielding layer must be grounded extensively at both ends.

Resolver: Suitable for extremely harsh environments (strong vibration, high temperature, oil pollution). Pin definitions: 3/4 (SIN+/-), 5/6 (COS+/-), 7/8 (EXC+/-, excitation signal). The signal line of the rotary transformer also needs to be strictly shielded.

4. EMC rules

The servo system is a strong interference source. The following rules must be followed:

Shielded motor cables and shielded encoder cables must be used, and the shielding layer must achieve large-area contact through metal connectors or 360 ° grounding clamps. Single point grounding through pins is strictly prohibited.

The motor cable should be as short as possible to avoid winding and forming a loop inside the control cabinet.

A central grounding point (CEP) should be installed inside the control cabinet, where all grounding wires converge in a star shape.

Inductive loads (contactor coils, relays) must be connected to the nearest freewheeling diode (DC) or impedance capacitance absorption circuit (AC).

Debugging, Running, and Performance Data Interpretation

1. Debugging process

Before the first power on: check all wiring (especially PE grounding continuity), check brake function, and check emergency stop circuit.

Parameter recognition: Connect to EPAS engineering software, read the motor electronic nameplate through the controller, and automatically complete parameter configuration. For the solver version without an electronic nameplate, manual input of motor parameters (pole pairs, torque constant, back electromotive force constant, etc.) is required.

Trial operation: First, test in low-speed JOG mode to confirm that the motor rotation direction, encoder feedback direction, and brake action logic are correct.

2. Torque speed characteristics

The manual provides detailed torque speed curves for each motor model. Understanding these curves is crucial for selecting and setting controller limits correctly:

S1 working system (continuous operation): The area below the curve is the continuous working zone of the motor. In this area, the temperature rise of the motor does not exceed the insulation level (F level, 155 ° C). For example, SM 100 40 050 can continuously output a torque of approximately 3.5 Nm at 4000 rpm.

Peak torque (MSM): The horizontal line at the top of the curve represents the peak torque output capability of the motor at a given bus voltage. This torque can only be output for a short period of time (usually a few hundred milliseconds), depending on the peak current limit of the controller.

Reduced capacity use: When the ambient temperature exceeds 40 ° C or the installation altitude exceeds 1000 meters, the capacity must be reduced. For every 1 ° C increase, the rated current decreases by 1%; At an altitude of over 1000 meters, for every 100 meters increase, the performance decreases by about 1%.

3. Temperature monitoring

The SM motor stator winding is embedded with a triple PTC thermistor (CPTC), with a switching temperature of 130 ° C. This signal must be connected to the motor temperature monitoring input of the driver. When the winding temperature reaches 130 ° C, the resistance of the thermistor rises sharply, and the driver should trigger an alarm and take measures to reduce power or stop the machine for protection.