Motor Mechanical Design

NeqSim provides a MotorMechanicalDesign class for the physical and mechanical aspects of electric motor specification, complementing the electrical design handled by ElectricalDesign and ElectricalMotor. Together with EquipmentDesignReport, this enables a complete motor and equipment design from a single process simulation result.

When to Use

You need …	Use class
Motor electrical sizing (kW, voltage, efficiency class)	`ElectricalDesign` / `ElectricalMotor`
Motor physical design (foundation, vibration, cooling, bearings, noise)	`MotorMechanicalDesign`
Combined mechanical + electrical + motor report	`EquipmentDesignReport`

Standards Reference

Standard	Scope	Used In
IEC 60034-1	Rating and performance, derating	Altitude and temperature derating
IEC 60034-5	Degrees of protection (IP code)	Enclosure / IP rating
IEC 60034-6	Methods of cooling (IC code)	Cooling classification
IEC 60034-9	Noise limits	Sound power level limits
IEC 60034-14	Mechanical vibration	Vibration grade A/B limits
IEC 60034-30-1	Efficiency classes (IE1–IE4)	Motor sizing (via ElectricalMotor)
IEEE 841	Petroleum/chemical industry motors	Foundation ratio (3:1), min bearing life
ISO 10816-3	Vibration evaluation — industrial machines	Vibration zone classification (A/B/C/D)
ISO 281	Rolling bearing life calculation	L10 bearing life
NORSOK E-001	Electrical systems (offshore)	Motor installation requirements
NORSOK S-002	Working environment	Noise limit 83 dB(A) at 1 m
IEC 60079	Equipment for explosive atmospheres	Ex marking for Zone 0/1/2

Quick Start

// Standalone — from known shaft power
MotorMechanicalDesign motorDesign = new MotorMechanicalDesign(250.0); // 250 kW
motorDesign.setPoles(4);
motorDesign.setAmbientTemperatureC(45.0);
motorDesign.setAltitudeM(500.0);
motorDesign.setHazardousZone(1);
motorDesign.setGasGroup("IIA");
motorDesign.calcDesign();

System.out.println(motorDesign.toJson());

// From electrical design — reads motor parameters automatically
Compressor comp = new Compressor("export", feed);
comp.setOutletPressure(80.0);
comp.run();

ElectricalDesign elecDesign = comp.getElectricalDesign();
elecDesign.calcDesign();

MotorMechanicalDesign motorDesign = new MotorMechanicalDesign(elecDesign);
motorDesign.calcDesign();

System.out.println("Foundation mass: " + motorDesign.getRequiredFoundationMassKg() + " kg");
System.out.println("Vibration zone:  " + motorDesign.getVibrationZone());
System.out.println("Cooling code:    " + motorDesign.getCoolingCode());
System.out.println("L10 bearing life:" + motorDesign.getBearingL10LifeHours() + " hours");
System.out.println("Noise at 1m:     " + motorDesign.getSoundPressureLevelAt1mDbA() + " dB(A)");
System.out.println("NORSOK S-002 OK: " + motorDesign.isNoiseWithinNorsokLimit());

Design Calculations

1. Environmental Derating (IEC 60034-1)

Motors are rated at standard conditions: 40 °C ambient, altitude up to 1000 m. Beyond these limits, output must be derated:

Altitude derating:

\[f_{\text{alt}} = 1 - \frac{\max(0,\; h - 1000)}{100} \times 0.01\]

where $h$ is altitude in meters. Each 100 m above 1000 m reduces output by 1%.

Temperature derating:

\[f_{\text{temp}} = 1 - \max(0,\; T_{\text{amb}} - 40) \times 0.025\]

where $T_{\text{amb}}$ is ambient temperature in °C. Each degree above 40 °C reduces output by 2.5%.

Combined derating:

\[f_{\text{combined}} = f_{\text{alt}} \times f_{\text{temp}}\]

2. Foundation Design (IEEE 841)

Static load — motor weight:

\[F_{\text{static}} = m_{\text{motor}} \times g\]

Dynamic load — due to residual unbalance per IEC 60034-14 Grade A:

\[F_{\text{dynamic}} \approx 0.1 \times F_{\text{static}}\]

Foundation mass — IEEE 841 recommends a minimum 3:1 mass ratio (concrete foundation to motor weight) for adequate vibration isolation:

\[m_{\text{foundation}} = 3 \times m_{\text{motor}}\]

Foundation type recommendation:

Motor Power	Foundation Type
< 75 kW	Steel baseplate on concrete pad
75 – 500 kW	Concrete block foundation
> 500 kW	Concrete block with spring isolation

3. Cooling Classification (IEC 60034-6)

IC Code	Description	Power Range
IC411	TEFC — totally enclosed, fan-cooled	≤ 315 kW
IC611	Separate external fan (forced ventilation)	315 – 2000 kW
IC81W	Water-cooled (closed circuit)	> 2000 kW

Heat dissipation is estimated from motor efficiency:

\[Q_{\text{loss}} = P_{\text{shaft}} \times \left(\frac{1}{\eta} - 1\right)\]

4. Bearing Selection (ISO 281)

Motor Power	Bearing Type
< 200 kW	Deep groove ball bearings
200 – 1000 kW	Cylindrical roller bearings (DE), ball (NDE)
> 1000 kW	Cylindrical roller bearings (both ends)

L10 life per ISO 281:

\[L_{10} = \left(\frac{C}{P}\right)^p \times \frac{10^6}{60 \times n}\]

where $C$ is dynamic bearing capacity, $P$ is equivalent load, $p$ = 3 for ball or 10/3 for roller, $n$ is speed in RPM. IEEE 841 requires minimum L10 of 3 years (26,280 hours) continuous operation.

5. Vibration Analysis (IEC 60034-14 / ISO 10816-3)

IEC 60034-14 Grade A limits (maximum vibration velocity at bearing housing):

Power Range	Max. Vibration (mm/s RMS)
0.16 – 15 kW	1.6
15 – 75 kW	2.5
75 – 300 kW	3.5
> 300 kW	4.5

ISO 10816-3 classifies the operating condition into zones:

Zone	Condition	Action
A	New machine	Normal operation
B	Long-term acceptable	No action needed
C	Short-term acceptable	Plan corrective action
D	Damaging	Immediate shutdown

6. Noise Assessment (IEC 60034-9 / NORSOK S-002)

Sound power level limits depend on motor power and pole count per IEC 60034-9.

NORSOK S-002 workplace limit: 83 dB(A) at 1 m from equipment.

Sound pressure at 1 m is estimated from sound power level:

\[L_p = L_w - 10 \log_{10}(2 \pi r^2) \approx L_w - 8 \; \text{dB}\]

Note: Motors with VFD may produce 3–8 dB(A) additional noise from switching harmonics in the winding. This is flagged in design notes.

7. Enclosure and Protection (IEC 60034-5 / IEC 60079)

Zone	IP Rating	Ex Protection	Enclosure Type
Safe area	IP55	—	TEFC
Zone 2	IP55	Ex nA (non-sparking)	TEFC
Zone 1	IP55	Ex d (flameproof)	Flameproof
Zone 0	IP66	Ex d (flameproof)	Flameproof, enhanced

API Reference