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Manual OJ Electronics Stepper motor system 

MRHX-2/-4/-8Nm & DRHX-1055, -1220  

HO

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-DRHX-1055/1220-MAD5 

 

Hoval factory setting is for analogue use (0-10V) 

DI1: Rotor rotation 
DI2: Enable external rotor guard 
DI3: Signal from external rotor guard 
 

MHRX = motor    DRHX = control unit

 

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The DHRX control unit is programed with a Hoval custom made UDF file 

 

This manual is specific for the setup of the Hoval drive system in RHE 

 

For complete instructions, information, warnings (caution/ protection) see OJ's original manual.  
Also valid for Modbus or OJ's DRHX PC 

– Tool (link and QR-code: 

 

https://ojelectronics.com/hvac/products/oj-drhx-drives/

 

 

Introduction    

 

 
 

MRHX/DRHX cannot be repaired on site. Never attempt to repair defective DRHX control unit or MHRX motor. 
Contact Hoval for support. 

 

Ensuring safety before installation

  

Product MRHX/ DRHX 

must only be installed by qualified personnel or people who have received appropriate 

training and have thus become qualified to install the product.

  

 

Controller DRHX contains dangerous high voltage when connected to the mains. Mains voltage must always be dis-
connected before any installation, service or maintenance tasks are performed on the product.  

 

The test button can be operated while mains voltage is connected. The stepper motor/ rotor can be started up using 
the test button, the 0

–10 V input signal or via the RS-485 interface (Modbus).  

 

Before connecting mains voltage to the DRHX controller 

all components, i.e. stepper motor, belt, pulley and rotor, must be installed correctly.  

all openings, covers and cable glands must be properly fitted and closed.  

 

To maintain the specified enclosure rating, unused cable glands should be replaced with blank glands/ plug.  

 

Controller DRHX contains capacitors which become charged during operation. These capacitors can remain 
charged even after the power supply has been cut off. There is a risk of severe personal injury if the 
connection terminals or wire ends are touched before these capacitors have been completely discharged.  
The discharge time is about 3 minutes under normal conditions. 

 

Product use

  

DRHX controller is used to regulate the speed of a rotary heat exchanger in air handling units. Controller DRHX can 
only be used to control MRHX stepper motor, supplied by OJ Electronics A/S. Never try to connect or control other 
types of stepper motor.  

 

Technical specifications       

 

The controller and stepper motor is controlled by signals or commands from an external control unit in the AHU.  
DRHX controller has built-in stepper motor protection and has a built-in EMC filter. 

 

The product carries a manufacturer's warranty if installed in accordance with these instructions and applicable 
installation regulations. If the product has been damaged (e.g. during transportation), it must be checked and (if 
necessary) repaired by OJ Electronics A/S before the product is installed, connected to mains voltage and 
energized. 

 

 

No 4220637 Ver 3 2020-12-17/ SESTCH 

Contact  

 

 

Summary of Contents for DRHX-1055 MAD5

Page 1: ...efore connecting mains voltage to the DRHX controller all components i e stepper motor belt pulley and rotor must be installed correctly all openings covers and cable glands must be properly fitted and closed To maintain the specified enclosure rating unused cable glands should be replaced with blank glands plug Controller DRHX contains capacitors which become charged during operation These capaci...

Page 2: ...m 50Hz 150 170 200 400 rpm Voltage Input 50 60Hz V 1x230 1x230 1x230 Motor voltage V 3x0 200 V AC 3x0 200 V AC 3x0 200 V AC Motor power kW 0 055 0 110 0 220 Rated current A 0 6 2 4 2 4 Class of protection IP54 IP54 IP54 Weight motor kg 2 4 3 5 5 Weight controller kg 0 9 0 9 0 9 Shaft Ø motor mm 12 12 12 8 Nm torque at max 250 motor rpm but only max 5 Nm torque at max 400 motor rpm 6 ...

Page 3: ... to avoid false alarms and errors it is important to install it proper The stepper motor comes with four holes for attachment to a solid mounting plate The mounting plate must be firmly attached to the chassis of the rotary heat exchanger or AHU see figure 12 2 1 marked 1 Do not use vibration dampers or springs Must be mounted on a fixed motor bracket ELECTRICAL INSTALLATION Potential equalization...

Page 4: ...pushing the wire into the terminal without using tools Alternatively the terminal spring can be loosened by pressing it lightly with a screwdriver or similar implement See fig 13 9 Stripped wire ends or end sleeves must be between 8 and 10 mm Wires can be removed by carefully loosening the terminal spring by pressing lightly with a screwdriver or similar implement See fig 13 9 Cable entries cable ...

Page 5: ...the connector from the cable from the DRHX extension cable The connector can be separated again by releasing the locking pawl on both sides of the connector on the motor cable and pulling the 2 connectors apart The extension cable should be connected to the terminals marked U Brown V Black W Blue PE Yellow Green If rotation of rotor is wrong switch the V black and W blue cable to change motor dire...

Page 6: ...changer from Hoval The DRHX series is equipped with 4 DIP switches for setting e g the stepper motor size and maximum motor speed DIP 1 2 motor size DIP 3 4 motor rpm see table 15 1 1 and 15 1 2 Required motor rpm is calculated by Hoval Depends on rotor Ø pulley Ø rotor and motor torque and given rotor rpm See table 15 1 3 Table 15 1 3 ...

Page 7: ... long the button is pressed in Running Test for RHE Belt should be mounted on rotor and pulley Start the test by pressing and continuously holding the test button The controller will enter test mode Visible in display and LED will be orange The test will remain active until the test button is released During this test run the motor will rotate with a maximum speed of 100 rpm Stop the test by relea...

Page 8: ...ies of rotor monitoring systems internal and external The factory setting is Internal rotor guard external is an option Hoval option RG3 Internal rotor guard The internal rotor guard monitors the rotation of the rotor by measuring the electronical signal returning from the motor will take place every 10 seconds After five consecutive failed detections within 1 hour the alarm E01 is given see page ...

Page 9: ...g signal Built in protection If the temperature inside DRHX overstep 95 C DRHX will attempt to reduce its internal heat generation by reducing the amount of current that is sent to the stepper motor DRHX has built in current limitation for the protection of stepper motor and cables and can therefore not supply more current than it is rated to see technical data page 2 DRHX is short circuit protect...

Page 10: ...turn green See point 8 7 If the stepper motor continues to run for more than one minute a recalibration needs to be done Recalibration Press and keep pressing the test button until LED flashes orange can take 10 50 sec Remove your finger from the button and the LED will turn green the pulley internal rotor guard has been calibrated 8 After turn off the DRHX controller and mount the belt Start norm...

Page 11: ...st page 10 Make the test calibration again see page 10 If the motor is too powerful for the rotors load large motor to a very small load The rotor torque is lower than the internal rotor guards minimal torque limit for chosen type of DRHX MRHX system i e spare part for old RHE Exchange type of MRHX motor and if needed DRHX controller so its fits the rotor type Contact Hoval for support E06 Wobblin...

Page 12: ...at the DRHX has a signal connected to the Start Stop input digital input Din 1 2 or 3 depending on the configuration Lacking 0 10 V DC control signal Check that DRHX receives an operating signal 1 1 V on 0 10 V In Active alarm Read active alarms via the display and remove what is causing the alarm see page 11 can also be read by using DRHX PC Tool or via Modbus The stepper motor has been stopped 5...

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