Fans by Fantech Electronic Catalogue

MOTOR INFORMATION

REFERENCE INFORMATION

2016

O-2

EXTERNAL ROTOR MOTORS

INTRODUCTION

The external rotor motor offers many attractive features such as space saving, compact

design, optimum cooling, full speed controllability and low starting currents.

Single and three-phase motors are produced to the highest International Quality

Assurance Standards.

Sealed-for-life ball bearings are fitted throughout the range with an L

life expectancy

of approximately 40,000 hours depending upon conditions of operation.

TEMPERATURE RANGE

The motors are designed to operate in the ambient temperature range of -15°C to

+40°C, but external rotor motors are often capable of operating in higher ambient

temperatures. Should you have such a need, refer your enquiry to one of our sales

offices.

ENCLOSURE STANDARD

The minimum is IP44 in accordance with DIN40050 and AS 60529: 2004.

SPECIAL FEATURES

Speed Control

External rotor motors are inherently suited to speed control using either electronic or

auto-transformer controllers. Refer to page

M-1

for details of the range of controllers

available.

Three phase external rotor motors can be speed controlled using Inverters with the

following restrictions:

1. Inverter output frequency must not be set over 50Hz. External rotor motors are

sized to suit the fan impeller at the maximum synchronous speed and do not have

the reserve capacity to provide the extra power required for faster speeds.

2. All frequency Inverters must include “all pole effec

tive sinusoidal filters”

3. DV/DT filters are not a suitable replacement for “a

ll pole sinusoidal filters”

te that warranty is void if an all pole sinusoidal filter i

s not used when speed

controlling an external rotor with a frequency inverter.

Care must be taken when selecting speed controllers as the amperage drawn

by some motors when being speed-controlled, can exceed the rated full load amps.

This characteristic is more apparent at approximately 70% of full speed and must be

considered when selecting the controller to ensure the controller rating is sufficient for

all conditions.

Whilst the drawn amps may exceed the nominal nameplate amps, there is little

likelihood of damage being done to the motor. The overload should be sized to

accommodate the excess amperage.

A number of identical fans can be controlled from a single controller but the total amps

of all the motors must not exceed 85% of the controller rating.

STAR/DELTA MOTORS

Most three-phase external rotor motors used with backward-curved centrifugal fans are

fitted with 2-speed star/delta motors as standard.

These motors enable full speed to be obtained when connected in delta and a reduced

speed when connected in star. The ratio of the speeds obtained is approximately 1.3:1

(reduced speed in slip) which approximates to a slightly higher speed than the next

synchronous speed down.

These speeds can be obtained by connecting directly to either delta or star.

Alternatively, by using a star/delta switch, either speed can be obtained at will. Details

of this product is given on page

M-7

THERMAL CONTACTS

Thermal contacts are fitted as standard to all external rotor motors.

Embedded deep in the windings of the motors, the contacts are bi-metal cutout design

which are temperature-dependent. Should the temperature of the motor rise to the limit,

the bi-metal cutouts activate and cut off the power, thereby providing full protection

to the motor.