UL approval for DRHX range creates new options for you

OJ Electronics has obtained UL approval for our popular DRHX range! This extends the reach of our energy-efficient ventilation systems, which are based on the use of a stepper motor and field-oriented sensorless motor control. The DRHX range is popular and we are pleased that you can now use it in even more markets.

Popular drive gets the UL stamp of approval

The DRHX drive range has proven to be very popular – so popular, in fact, that you have asked to be able to use it in even more markets.

As Preben Jessen, Head of Drive Products at OJ Electronics, explains:

“The DRHX drive is based on combining a stepper motor and field oriented sensorless motor control to ensure energy-optimised heat recovery and precise temperature control. It’s a patented solution that gave our customers an entirely new way of maximising the efficiency of their ventilation systems – and having seen how well it works, they wanted to be able to use it in even more markets.

Preben Jessen, Head of Drive Products, OJ Electronics

Individual parts were already UL approved

To enter the US and Canadian markets, the range needed UL approval. The Danish designs were already perfected for the European market and would simply require a few adjustments to get the UL approval. “The individual parts and materials for the DRHX were already approved, but the range itself needed the stamp of approval,” recalls Preben Jessen. “It required some small changes, which our team found the best solutions for.”

Bringing familiar benefits to new markets

Overall, Preben Jessen describes the process as smooth sailing: “We design our products according to very strict quality criteria, so we were quite confident about subjecting them to external examination,” he relates. “The process was mostly about obtaining external confirmation of what we already knew – and then there were the minor adjustments like updating the product labels to show temperature ranges in Fahrenheit as well as Celsius.
Customers who already know the DRHX can confidently explore new markets with the UL approved version of the proven OJ solution, as it has the same benefits and quality.”


In stock now – and ready for you to use in the USA and Canada

With the process complete, OJ Electronics instigated production immediately. “We now have the UL approved DRHX range in stock, and several of our customers have already received their first shipment and are currently demonstrating the DRHX benefits to customers in the USA and Canada. We’re sure they’ll see the potential inherent in having a direct drive solution that has no gears, no wear parts, no oil leaks, no losses – and great energy efficiency!”


UL approval details

OJ’s DRHX range is now cULus – UL 61800-5-1 and C22.2.274 – recognised! The DRHX products are solid-state variable speed AC inverters convert a fixed frequency into a variable frequency and maintains the required Volts/Hz (V/f) ratio. This makes it possible for the AC and PM motor to function and the optimum speed. As the DRHX range is designed for industrial machines (in accordance with NFPA79) and incorporate internal solid-state short circuit protection. It may, however, not be suitable for installations in accordance with the NEC (NFPA70), as the products are permanently connected using cable connections.

The motor itself does not refer to the UL 61800-5-1 standard, but to the following standards:

UL 1004-1Rotating Electrical Machines – General Requirements
UL 1004-6 Servo and Stepper motor
CSA C22.2 No. 100Motors and Generators

The motors are UL approved as unlisted components according to UL 1004 / CSA C22.2.100 for use in combination with OJ DRHX drive series.


The DRHX benefits in brief

  • UL and CSA approval
  • Great for energy efficiency
  • Direct drive, no gears – no oil leaks
  • No wear parts
  • No losses
  • Compact motors for easier design processes
  • You can find more details on the DRHX range here

The DRHX drives are now UL approved, enabling you to bring the benefits to more markets than ever.

Know-how createsCurious to
know more?

- or do you have a question regarding the article ? Please don’t hesitate to contact

Preben Jessen, Head of Drive Products

+45 24 99 39 46 [email protected] Rotor products