VariMax50 NG
(Next generation)

VariMax50 NG
(Next generation)

Article no. F21050305    VariMax50 NG

VariMax50 NG is our latest control unit for rotating heat exchangers.

The control unit combines small dimensions with large capacity, and is very easy to fit and commission.

VariMax50 NG is intended for rotors up to 2500 mm with a rotor speed of max 12 rpm. If the rotor requires a faster rotor speed, the rotor diameter should be reduced.

VariMax50 NG is an alternative to VariMax UL/CSA.

The control unit is supplied in an enclosed format and must be combined with our VariMax motor50 NG.
The VariMax NG series can be included as components in one of our Drive sets.

  • Interal rotation monitor
  • User-friendly
  • Stable aluminium enclosure
  • Compact dimensions for embedding
  • Input signal 0-10 V
  • Alarm retention
  • CE-marked
  • Five-year product warranty

Connection diagram


Function description
The VariMax50 NG together with VariMax motor50 NG constitutes a modern combination with specific additional functions for the optimal control of a rotating heat exchanger. The VariMax-motor50 NG is a stepping motor with substantial torque over the entire speed range. This means that the speed of a thermal rotor is between 0,1-12 rpm.

Input signal 0-10 V
The heat exchanger rpm is governed by the control unit so that the heat exchanger's degree of efficiency is proportional to the input signal from the control centre.

Ceaning function

When the rotor has stopped for 10 minutes, the cleaning function is activated and the rotor starts to rotate. As a warning, the rotor first rotates for 6 seconds at a motor speed of 5 rpm, the rotor is then stationary for 3 seconds. After this, the actual cleaning starts, for a random time, between 10 to 20 seconds with the motor at 20 rpm. 


Rotation monitor
The VariMax50 NG has an internal rotation monitor. The rotation monitor is patent pending. 

This is activated when the DIP switch for the “External rotation monitor” is in the OFF position. 

The internal rotation monitor performs measurements at different times, depending on whether the speed of the motor is above or below 37 rpm.

At a motor speed above 37 rpm, the measurement begins when the speed is stable, normally starting after about 30 seconds, after which measurements are carried out continually. The yellow “Rotation” LED flashes after each completed, approved measurement. The time between the measurements varies from 22 seconds to nearly two minutes.

At a motor speed below 37 rpm, the control unit will increase the speed to 37 rpm at two-hour intervals. At start-up, this measurement will start after 10 minutes. The speed will remain steady for 2 minutes, while the actual measurement is being performed. To verify the measurement, an additional measurement is conducted 10 minutes later. If both of these measurements are positive, i.e. everything is normal, the next measurement will not take place until two hours later.
This sequence is then repeated with the same time intervals, provided the motor speed is below 37 rpm.

As an alternative, the VariMax50 NG can have an external rotation monitor (magnet mounted on the rotor with an associated rotation monitor). This is connected at terminal connections 9 and 10, and the DIP switch for the “External rotation monitor” should be in the ON position.

External faults
The control unit trips and generates an alarm in the event of
Over/under temperature

Motor fault
Short circuit phase-phase or phase-earth.

Internal fault
Alarms and trips if an internal fault occurs in the control unit.

All alarms are remaining

Manual speed
Possibility of externally controlling the speed.
The speed is adjusted with a separate potentiometer. 

DIP switch for manual run at high or low speed rpm.

Technical data
VariMax50 NG
Connection voltage
1x230-240 V +/-15% 50/60 Hz
Power input max
222 W
Input current max
1.65 A
External fuse, max
10 A
Output voltage*)
3x0-260 V
Output current, max
2,0 A
Output frequency
0-312 Hz
Acceleration and retardation time
30 sec
Ambient temperature, non condensing
-40 - +45 °C
Protection form
0.8 kg
Dimensions, HxWxD
162x195x56 mm
Exact value cannot be obtained with a digital measuring instrument

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