Low voltage motors for maximum safety and security as well as availability in the oil and gas industry

General description

The LOHER VARIO Ex nA series has a welded steel enclosure for the highest degree of variability and versatility. Flange rings at the ends of the enclosure increase the torsional stiffness and ensure a vibration-proof mechanical design. The steel version allows various bearing concepts, dimensions can be adapted and a wide range of instruments can be mounted. The surface cooling using flat ribs combined with a defined inner cooling circuit with shaft-mounted fan inside the motor ensure optimum motor utilization.
The copper bar rotors used as standard allow the starting and operating parameters to be optimized for each and every application.


Technical data overview

Brief overview



Shaft heights:

355, 400, 450, 500, 560

Power range:

90 kW - 2100 kW

Number of poles:

2 - 16 poles, higher pole numbers on request

Voltage range:

380 V - 950 V

Rated voltage:

380 V / 400 V / 415 V / 500 V / 660 V / 690 V

Frequency converter:

Line and converter operation

Degree of protection:

IP55, IP56, IP65, IP67

Cooling type:

IC 411, IC 416, IC 71W

Type of construction:

IM B3, IM B35, IM V1


Welded steel


Roller bearings, sleeve bearings



Explosion protection:

II3G Ex nA II T3

Type of protection: without explosion protection


Noise level:

max. 85 dB(A) (Load, 50 Hz), lower noise versions are available


  • Also available for exceptional requirements - such as dust explosion protection.

  • Corrosion protection using special paint finishes according to the manufacturer's standard or customer's specification.

  • The motors are available as special version for polar regions down to -40 °C (without pre-heating of the motor) or desert regions up to +60 °C.

  • When required, vertical motors can also be equipped with thrust bearings for high axial and radial loads.

  • Wide range of connection systems for large cable cross-sections, high short-circuit strength or phase-segregated version.

  • Optimized starting and operating parameters and high efficiency by using copper bar rotors as standard.

  • With water jacket cooling IC71W up to 60 % higher power density - compact and low noise. Admirably suited for converter operation with constant load torque.

Customer benefits

  • Complies with almost all of the user requirements and specifications (no deviation philosophy)

  • Engineered based on international standards (ATEX, NEPSI, GOST-R certified)

  • High level of acceptance in the various sectors. For instance, Shell and DOW recommend these motors

  • Complete project documentation guarantees minimum planning costs

  • High degree of cost effectiveness and low operating costs as a result of the optimum electrical and mechanical values

  • High degree of variability and versatility using a welded steel enclosure (to adapt the dimensions, mounted components)

  • Up to 11 kV, pre-purging not necessary with proof according to risk assessment EN 60079-15

Typical applications

Used in Ex-Zone 2 for

  • Pumps

  • Compressors

  • Fans

  • Centrifuges

  • Branch Oil & Gas