Schorch KN Series IP23 Low Voltage Induction Motor

Overview

The Schorch KN series is a range of low voltage, three-phase squirrel-cage induction motors with open, ventilated IP23 enclosures, built by ATB Schorch GmbH in Mönchengladbach, Germany. According to the Schorch product overview, the Schorch KN covers frame sizes 250 to 400 and power outputs from 37 to 1,300 kW, with 2, 4, 6, 8 or 10 poles, efficiency class IE2 or IE3, and supply voltages from 200 to 690 V for both direct line and inverter operation. The frame is cast iron, insulation is thermal class 155 (F) utilised to class 130 (B), or class 180 (H) utilised to 155 (F), and cooling is to IC01 or IC06. Because a drip-proof IP23 motor is cooled by air flowing directly through the machine, it delivers high power from a compact, relatively light frame.

Seven Star LLC supplies the Schorch KN to power plants, water and desalination facilities, cement and mining operations, oil and gas utilities and industrial plants in the Sultanate of Oman and the GCC. Seven Star LLC already lists Schorch high voltage motors, and our Muscat team helps customers match replacement and new Schorch KN motors to existing frames, mountings and duty, from our office in Muscat.

Design and Construction of the Schorch KN

The Schorch IP23 operating manual covers ventilated-enclosure low voltage machines of model sizes 180M to 400X, with the basic model designated Type KN7. These machines have squirrel-cage rotors and are suitable for indoor installation at altitudes up to 1,000 m above sea level and ambient temperatures from -20 to +40 °C, unless the rating plate states otherwise. Cooling air normally flows from the drive side to the non-drive side, and the manual requires a clearance of at least one quarter of the air intake diameter between the intake and any driven equipment or covers, and warns that exhaust air must not be drawn back in.

Pipe-ventilated versions of the Schorch KN take in and discharge air through a ducting system. As supplied they correspond to IP00, and IP54 can be achieved through suitable modifications to the piping, provided the pressure drop in the external circuit stays within the tabulated limits. For example, at 1500 rpm the manual lists required air flows from 8 m3/min for shaft height 180 up to 75 m3/min for shaft height 400. Each rotor of the Schorch KN is dynamically balanced with a full, half or no key, and the drive element must be balanced to match. Motors with shaft heights of 180, 200, 250, 280 and 315 have one housing length per frame, with the S, M, L and X foot positions cast into the base.

Key Features

The main characteristics of the Schorch KN low voltage motor are:

• Power outputs from 37 to 1,300 kW in frame sizes 250 to 400.
• IE2 or IE3 efficiency class, with 2, 4, 6, 8 or 10 pole designs.
• Supply voltages from 200 to 690 V, for line or inverter operation.
• Rugged cast iron frame with IP23 drip-proof enclosure and IC01 or IC06 cooling.
• Thermal class 155 (F) insulation utilised to 130 (B), or class 180 (H) utilised to 155 (F), for a thermal reserve.
• Mounting arrangements B3, B35, B5, V1, V3, V5 and V6.
• Regreasable rolling bearings with a grease volume regulator and M10 x 1 grease nipple to DIN 3404 as standard.
• Optional winding and bearing temperature sensors, space heater and measuring nipple for bearing monitoring.

Bearings and Maintenance

The manual explains that the operational safety of the Schorch KN depends on following the lubrication schedule. Bearings are lubricated in the factory, and the relubrication interval and grease quantity are stamped on the rating plate. Basic model machines can be refilled without cleaning using a lithium-soap rolling bearing grease K3k to DIN 51825, such as SKF LGMT3 or Shell Alvania G3; a change to a grease with a different soap base requires cleaning of the bearing assemblies and consultation with the manufacturer. Relubrication is carried out with the motor running. Motors fitted with cylindrical roller bearings are shipped with a transport locking device to prevent bearing damage. The manual also gives bearing change procedures for shaft heights 180 to 315 and 355 to 400.

For vibration, the manual refers to DIN ISO 3945 and gives limiting values on the bearing housing for rigid foundations of 5.5 mm/s for alarm and 11 mm/s for switch-off. Coupling alignment should leave no more than 0.03 mm residual error in angular and parallel alignment, checked again with the motor warm. Before commissioning, insulation resistance is measured with a maximum of 630 V DC; new windings exceed 10 megohms.

Industrial Applications

Open drip-proof motors such as the Schorch KN are used where the motor is installed indoors in clean, dry machine rooms and a high power-to-weight ratio is valuable. Typical drives include pumps in water transmission and desalination plants, fans and blowers in power stations and cement plants, compressors, crushers, mills and conveyor drives. Inverter capability makes the Schorch KN suitable for variable speed pump and fan applications where energy savings are a priority.

In Oman, these duties appear in pumping stations, independent water and power projects, mining and cement operations around Sohar, Duqm and Salalah, and industrial estates near Muscat. Seven Star LLC supplies Schorch KN motors and their spare bearings and accessories to these customers across Oman and the GCC.

Selection Notes (General)

This section is general engineering guidance rather than manufacturer data. Choose an IP23 enclosure only where the installation is indoors and free of dust, moisture and corrosive air; outdoor and harsh environments call for totally enclosed IP55 or higher motors. Check derating for the local ambient temperature and altitude, since the standard basis is 40 °C. For inverter duty, confirm insulation and bearing protection requirements with the supplier.

Technical Specifications

Data for the Schorch KN from the ATB Schorch product overview and IP23 manual:

How to Order

To request a quotation for a Schorch KN motor, send Seven Star LLC the rated power, speed or pole number, voltage and frequency, mounting arrangement, frame size, efficiency class and whether the motor will run on an inverter, or simply the rating plate data of the motor you need to replace. The ATB Schorch IP23 manual is available for download on this page. You can also review the Schorch KV6535B high-voltage motor, the WEG W22 IE3 three-phase motor and the Siemens 1LA7 squirrel-cage motor. Seven Star LLC provides model selection support from Muscat for customers in Oman and the GCC.