20G11ND040AA0NNNNN — 755 Series AC Drive, 480V Three-Phase, 20 HP / 15 kW

The 20G11ND040AA0NNNNN is a 480V three-phase AC drive from the 755 series, rated at 40A output current — equivalent to approximately 20 HP (15 kW) on a standard four-pole induction motor. The 755 platform is a mid-to-high-end drive family that supports multiple control modes from basic V/Hz through to closed-loop flux vector with encoder feedback, and carries a wide range of option card slots for communication, I/O expansion, and safety functions.

At 20 HP, this drive sits in a range where the choice of control mode starts to matter for demanding applications. Pumps and fans run fine on V/Hz; compressors, extruders, and winders that need tight speed regulation under variable load benefit from sensorless vector; and servo-grade positioning requires the encoder feedback option. The 755 handles all three from the same hardware, configured through the option card slots and drive parameters.

Specifications

Parameter	Value
Part Number	20G11ND040AA0NNNNN
Series	755 Series
Output Current (Normal Duty)	40 A
Motor Power (approx.)	15 kW / 20 HP @ 480V
Input Voltage	380–480V AC, Three-Phase
Output Frequency Range	0–400 Hz
Control Modes	V/Hz, Sensorless Vector (SVC), Flux Vector (FV) with encoder option
Onboard I/O	6 digital inputs, 1 digital output, 2 analog inputs, 1 analog output
Option Card Slots	Up to 5 (communication, I/O, encoder, safety)
Dynamic Braking	Internal transistor; external resistor required
Enclosure	IP20 / Open Type (Frame 3)
Operating Temperature	0°C to 50°C (derate above 40°C)
Approvals	UL 508C, CE, C-Tick, RoHS

Thermal Management

The 755 Frame 3 (which covers the 40A variant) uses a heatsink-through-panel mounting option as an alternative to full panel mounting. With heatsink-through-panel, the heatsink and main cooling airflow are outside the enclosure, and only the control electronics are inside — this significantly reduces the heat load inside the panel and can allow a smaller enclosure.

For standard panel mounting, maintain the minimum clearances: 100 mm above and below for cooling airflow, and ensure the exhaust air from one drive doesn't recirculate into the inlet of the one above it. At 40A output, the drive's power dissipation at full load is roughly 300–350W depending on switching frequency — that's the heat the enclosure ventilation needs to handle.

Reduce PWM switching frequency if panel temperatures run high — dropping from 4 kHz to 2 kHz reduces drive losses by 15–20% at the cost of slightly more motor audible noise.
Ambient temperature above 40°C requires output current derating — 1% per degree Celsius above 40°C up to the 50°C maximum.
Altitude derating applies above 1000 m — reduce rated output current by 1% per 100 m above 1000 m.

Drive Protection Features

The 755 has a more comprehensive protection set than basic drives. Key protective functions active by default:

Electronic overload (I²t) — tracks thermal state of the motor, trips if sustained overcurrent exceeds the motor's thermal model. Configurable for motor class and cooling type.
Input phase loss — detects missing input phase. At 15 kW, single-phasing causes significant DC bus ripple and motor stress; the drive trips before damage occurs.
Ground fault — monitors output current imbalance. A developing ground fault on the motor or cable generates a trip before the fault progresses.
Stall detection — if motor speed drops below the expected value for the commanded frequency, the stall timer begins. Trip action is configurable: fault, reduce speed, or alarm only.
Safe Torque Off (STO) — hardware STO inputs are standard on the 755. With the STO input de-energized, gate pulses to the output stage are inhibited regardless of any speed command. This is a Category 3 / PLd safety function used for safe stop applications.

FAQ

Q: What communication options are available for this drive?

The 755 has up to five option card slots. Common communication cards include EtherNet/IP (20-COMM-E), DeviceNet (20-COMM-D), Profibus (20-COMM-P), and Modbus/TCP. The specific slot used for a communication card depends on the other option cards installed — consult the option card installation instructions for slot assignment rules.

Q: Does this drive support a Safe Torque Off function without a safety controller?

Yes. The STO hardware inputs on the 755 are hardwired safety inputs that don't require the drive to be connected to a safety PLC. They can be driven directly from a safety relay to achieve Category 3 / PLd safe stop without any controller involvement.

Q: Can the drive be mounted on its side or horizontally?

No. The 755 must be mounted vertically. Horizontal or inverted mounting blocks the internal cooling airflow path and will cause overtemperature faults under load.

Q: How is the drive's motor overload class configured?

Motor overload class is set via drive parameters, typically Class 10 (default) or Class 20 for motors with higher thermal mass or NEMA Design D characteristics. Set it to match the motor's thermal protection requirement — Class 10 trips faster under overload than Class 20.

Q: What is normal duty vs. heavy duty rating, and which applies here?

Normal duty (ND) is rated for loads with low overload requirements — pumps, fans, centrifugal compressors that rarely exceed 110% current. Heavy duty (HD) allows higher short-term overload (150% for 1 minute) for applications like conveyors, crushers, and cranes. The 20G11ND040AA0NNNNN is a Normal Duty configuration at 40A; the same frame hardware has a lower HD current rating if heavy overload capability is needed.

20G11ND040AA0NNNNN New 20G11ND040AA0NNNNN 755 Drive