FAQ - Mf-Flex (Motor - Technical)

Frequently asked questions

Are the belt drive motors different than the direct drive motors? »»

Yes, the most belt drive motors are standard norm-motors; all the Multifan motors (direct drive AND belt drive) are self-designed, special motors. A pulley construction in combination with a belt are used to drive the fans.

Do the Multifan motors have Service Factor (SF) 1,0? »»

All the fan motors are maximally charged and can be regarded as minimal SF 1,0.

What temperature range is class F insulation? »»

Class F means that the winding can withstand a maximum temperature of 155°C/311 F

How many insulation classes exist? »»

There are 4 classes: A, B, E and F

Can the motor be rewound? »»

Yes, however the wire type and quality and the number of windings must be the same. Cost aspects have to be considered too.

What is the acceptable frequency range? »»

Vostermans delivers fans in 50 or 60 Hz. Optional the fans can be made suitable for frequency control by adding extra coil insulation. The fans can be controlled back to 10% of their maximum air supply.

What reason is there for the terminal block and round eyelets »»

These connections create a very good contact surface and have advantages for the installers during service and installation.

Why is chosen for ball bearings rather than sleeve bearings? »»

The ball bearings create a higher efficiency (less friction and higher liveability), do not need any lubrication and a lower noise level is obtained. For controlled motors ball bearings create an improved performance and higher durability.

Variable speed – what is slowest speed the motor can be run at? »»

It is a TEAO (Totally Enclosed, Air Over) motor, so the minimum speed must be fast enough to have cooling air flow over the motor.
INSULATION: What temperature range is Class F insulation and how many classes exist?
Class F means the motor winding insulation can withstand a maximum temperature of 155°C/311°F. The maximum temperature allowed is a combination of the temperature rise of the coil windings plus the ambient temperature around the motor.
The motor industry insulation classes are:
A = 105°C/221°F
E = 120°C/248°F
B = 130°C/266°F
F = 155°C/311°F
H = 180°C/356°F

THERMAL PROTECTION: Do Vostermans Ventilation motors have thermal protection? »»

Yes, single phase motors standard have a thermal protection. The motor will automatically shut off when the motor temperature reaches 284°F/140°C, and will reset itself when the motor temperature drops to 257°F/125°C.
Three phase motors do not have the thermal protection as standard. The motors can be ordered special with thermal protection. Otherwise the protection need to be incorporated in the external power supply, before the motor.

AMBIENT TEMPERATURE RANGE: What is the minimum and maximum ambient temperature range the fan can be operated in? »»

Vostermans Ventilation fans are guaranteed for a range between -32°F/-36°C and 104° F/40°C. Higher temperatures can be approved, depending on the static pressure load, use of speed control, and availability of optional impellers.

SAFETY: What industrial approvals and certifications does Vostermans Ventilation have on the motors and fans? »»

Motors have UL 1004 recognition for safety for electric motors
Motors also have CSA C22.2 recognition for safety for electric motors
Motors are UL 507 recognized for outdoor application
CE (Europe) declarations (for 60 Hz versions) can be provided upon request.
Most fans are UL 507 listed and CSA C22.2 approved

MOTOR IDENTIFICATION PLATE: Explain the motor model number. As an example, what does 4E35 mean? »»

This identification is used on the Multifan motor only. It is not used on the Mf-Flex motor line. The alpha-numeric designation is on the the motor identification plate on the motor end cap. Using the example, 4E35:

RPM	50 Hz	60 Hz
2 pole	3000	3200
4 pole	1500	1600
6 pole	750	1000
8 pole	600	800

First number is the number of poles in the motor winding. This will also give you the
approximate motor and fan speed.

First letter is the electricity.
E is single phase.
D is three phase.
Last 2 or 3 numbers represent the fan diameter size in centimeters.
20 = 8"
25 =10"
30 =12"
35 =14"
40 =16"
45 =18"
50 =20"
56 =22"
63 =24"
71 =28"
89 =36"
92 =36"
So the 4E35 is the motor for a 1,600 rpm, single phase electricity, 14" fan.

Vostermans Companies is not responsible for inaccurate or incomplete data. In case of any questions and/or remarks please contact .