RHM International High Voltage Lab

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29 Flagstone Drive
Hudson, NH, 03051

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Key Contact Personnel:
Bob Middleton, Chief of Technology & Engineering bob.middleton@rhmintl.com
Haizhen Wang, Design Engineer haizhenw@rhmintl.com
Brian Hall, High Voltage Test Engineer brian.hall@rhmintl.com

RHM International are specialists in the development and manufacturing of high voltage dry insulated equipment and components. To support its North American customers RHM International owns and operates one of the largest HV test labs in the northeastern USA, located in Hudson, NH.

Primarily built for the testing of its own products, RHM International’s lab in southern NH was designed and built from the ground up.  Strict safety protocols, highly qualified test personnel and detailed test procedure documentation are in place at our New England high voltage test facility to provide our customers with the testing services needed to meet their requirements for manufacturer certified test results.

We are now offering testing services for companies needing dielectric tests for their product development projects who can accept test results from a first party test lab. Our team of skilled engineers can offer customized test plans, scheduling flexibility, comprehensive and accurate test reports at very competitive rates.

Year Founded: 
2004 – Founding of RHM International, to develop international awareness and markets for HV DryShield® and RIF® dry type and paper-free high voltage insulation technology.
2018 – The New England High Voltage Test Service Laboratory was brought online and is fully operational

Major Export Markets Served: Worldwide



All tests are performed in accordance with IEEE, IEC, CAN/CSA and other applicable standards, including any individual customer specified needs. We strive to have a lean operation, streamlined for efficiency, and are pursuing ISO 9001 certification.

High Voltage Laboratory

Dimensions of Main Test Hall: 28 m width x 28 m length x 17.5 m height.
Our test bay is fully enclosed in a six-side Faraday cage with EMI filters.
4.2 m width by 4.2 m height overhead door.
5-ton overhead bridge crane spanning the entire test bay.

Power Source: A.C. 60 Hz at 480 V from the power grid is fed through isolation transformers and EMI filters before connecting to our test equipment.

Dielectric Testing Equipment:
Lightning Impulse:

Impulse Voltage Generator, 2800 kV, 280 kJ
Lightning Impulse, Full wave 1.2/50 μs
Chopped Lightning Impulse 2-6 μs to chop
Switching Impulse (dry) 250/2500 μs

A.C. Testing:
1000 kV / 2000 kVA LC 60 Hz compensation system. ISO/IEC 17025 calibrated.
Designed for robustness and flexibility, this equipment performs power-frequency withstand 1-minute tests.
This is also the test object’s power source for partial discharge and external reference dielectric dissipation factor tests.

Partial Discharge Testing:
Omicron MPD-600 high precision test equipment. Our laboratory’s Faraday cage provides a background level of < 1 pC.

Dielectric Dissipation Factor and Capacitance Testing:
Up to 400 kV for external reference testing for PF/tan δ and capacitance measurement.

Test for Accuracy of Current Transformer:
Direct and indirect test methods for CT accuracy with primary current rating up to 8000A.

Typical Test Objects:
Instrument Transformers, Apparatus Bushings, Wall Bushings, Bus Bars, Cables, Cable Terminators, Insulators, Capacitors and Inductors.

Our staff is trained in first aid, CPR, the use of AEDs and equipped with task appropriate PPE. Fire suppression systems are in place.
Test service clients may visit our site to witness their products being tested in accordance with our safety protocol.

Certifications Offered:
Customized type and/or routine test reports are tailored to the specific parameters of your test object and requirements.