Pump motors

Randax has wide selection of advanced motor solutions for various different pump applications. Solutions are generally direct drive motors for power range of 10 – 3 000 kW and speed range of 100 – 5000 rpm. Randax supplies complete motors and also customized stator – rotor units (SRU) to be integrated into customers’ existing pump frame.

Motors are equipped with steel or aluminum frame and with air or liquid cooling. High efficiency Randax motors are always tailored for the customer’s application. Due to compact size and light weight of Randax motor or SRU, they can be fully integrated as a part of customer’s equipment.

Reference case 1:

Submersible dredging pump motor 1400kW@360rpm

Randax has developed and delivered stator – rotor units in size of 1400kW@360rpm for dredging pump application. This stator-rotor unit has been installed to submersible dredging pump motor frame made by Marotechniek. Marotechniek is Randax customer and partner in the Netherlands. This Permanent Magnet motor will be used in direct drive submersed dredge pump which will be installed on hopper dredger ship built by Damen shipyards.

The 1400 kW size electric motor is the world largest Permanent Magnet motor used in a submersed dredge pump drive to date. The air filled motor is smaller, lighter and more efficient than conventional asynchronous oil filled ones – with a staggering measured very high efficiency of 97% including friction of all bearings and mechanical-seal.

The hopper dredger is designed for mining marine aggregates at -55 m below sea level. The submersed dredge pump is directly driven by a continuous electric motor – that is, without a gear box in between. Moreover, the electric motor forms an integral part of the trailing pipe structure.

Both Randax and Marotechniek are expecting in near future huge growth in a market for submersible dredging pump motors.

Reference case 2:

Integrated Randax® special pump motor

The hygienic SHS is specially designed for demanding pumping applications in the process industry, which require high process purity and reliability. The SHS is the result of three-way development cooperation between Wetend Technologies, the manufacturer of TrumpJet® flash-mixing process systems, the process pump manufacturer Sulzer, and the special motor manufacturer Randax.

Randax® motor technology enables the building of a sufficiently compact, light, economical and efficient integrated motor solution to fulfil the requirements of the SHS injection pump. The motor design takes account of the demanding conditions and operation of the frequency converter, on the basis of high-quality reinforced isolation, advanced VPI impregnation and corrosion-resistant materials.

SHS-motor type 




Nominal current

23,5 A   46,0 A   69,0 A

Nominal voltage 

400 VAC   400 VAC   400 VAC  

Nominal frequency 

205 Hz     205 Hz     205 Hz    

Rotation speed

4100 RPM 4100 RPM 4100 RPM

Nominal power

15 kW    30 kW 45 kW

Nominal torque

35,0 Nm  70,0 Nm   105 Nm


94 %  96 %   97%


48 kg 66 kg 85 kg

Frame material    

Stainless steel  Stainless steel Stainless steel