Invention House is a reliable source for 20hp, 230-volt, 400hz motor control drives for OEM application. Invention House has been designing and building custom motor drives for over 20 years. We have built drives for commercial and military applications, including demanding environments such as desert conditions and aviation.
Our speciality is custom motor drives, where we integrate the drive, power supply, and PLC on one or two boards.
Application for our custom, reliable 3-phase 230-volt, 400hz (input / outbput) motor drives include:
Invention House 3-phase, 230volt drives are designed to meet demanding specs, including ambient temperatures from -45c to +55c, and withstand 40g shock and 2g rms vibration. This drive supports 400hz input or output. Drive control is set up through standard terminals or Modbus. Our 3-phase, 230-volt drives require minimal cooling – just 5 cfm across the heat sink fins.
New from Invention House: 3-Phase, 400Hz capable variable frequency drive (VFD)
Currently tested in heavy lift environments exceeding 10,000 lbs, Invention House’s new 400Hz air-crafted rated 3-phase motor drive is ideal for manufacturers seeking a custom variable frequency drive to solve aircraft electric motor control needs. The Invention House 3 Phase Aerospace/Aircraft electrical motor drive is capable of 50/60/400Hz output. This ruggedized drive is designed to withstand temperatures from -40C to +55C and up to 40g shock and 2grms vibration, making it the perfect drive for on-aircraft operations, including helicopter and fixed-wing aircraft. Our new aircraft-rated drive weighs in at 10lbs(4.5kg) and is significantly lighter than commercial drives of the same rating which generally weigh 30lbs or more, thus creating space and weight savings for improved aircraft operations.
Controlling variable frequency drive shock hazard is an important part of proper VFD maintenance and management. The risk of electrical shock stems from the manner in which motor drives assume control of motor voltage supply.
Electrical Shock Origination & Control
When a drive is energized but disabled, and the motor is stopped, it’s NOT open…there is no air between the line voltage and the motor leads. To safely work on the motor, the line input to the VFD must be opened. Some newer drives have a feature called “safe torque off,” which also is NOT a contractor. When the “safe torque off ” is active and the motor is stopped, the power connection is NOT open…there is no air between the line voltage and the motor leads. Controlling variable frequency drive shock hazard can be accomplished by opening the line input to the VFD. “Safe torque off ” simply interrupts the gate power to the output transistors so that rotation is not possible. The transistor and the diodes still connect the motor leads to the line voltage, which can cause a shock hazard unless the line input to the VFD is opened.
Arc Flash Implications
The electrical shock potential from a VFD is distinct but potentially related to arc flash. Arc flash, also sometimes referred to as “flash over”, stems from an arc fault, which is a severe instantaneous electrical discharge that results from a low-impedance connection through air to ground or another voltage phase change in a electrical systems. A gaseous fire ball is created filling the space immediately in front of an open cabinet. Arc flash is deadly and all precautions must be made to prevent it.
Controlling variable frequency drive electrical shock conditions is a #1 priority at Invention House. We take great precaution when building and working on custom AC motor drive solutions for our OEM and military clients.
Consult the users guide, website FAQ page or the help center of your VFD manufacturer before working on any VFD.
There are 5 critical variable frequency drive (VFD) limitations that should be considered when selecting the proper VFD for motor speed control applications.
A VFD is an electronic circuit that controls the speed of an electric motor by adjusting both the voltage and the frequency applied to the motor. Prior to VFDs, motor speed was controlled through inefficient voltage regulators (think light dimmer switch!) or mechanical means – pulleys, gears, or transmission systems. The original VFDs filled large cabinets and were unreliable. Today, VFDs are smaller than a shoe box, reliable, and are used in almost all industrial applications, pumps, fans, conveyors, machining, compressors, etc. VFDs can also be employed on linear motors to generate vibration, which is often critical in “shaker machines” used in product separation and packaging. However, VFD’s are not miracle workers and there are important limitations. If you are already using VFDs or are considering their use for the first time, these limitations should be considers. Learn more facts about VFDs in my paper 5 Basic VFD Facts.
A VFD can make a motor run slower than rated speed, however a major point of consideration at low speed is cooling. A typical electric motor is cooled by a fan on its shaft; at low speed the fan moves less air and at some point the motor will over heat. This is generally not a problem with centrifugal loads such as fans, pumps, and blowers because the torque required by the load drops drastically with decreasing speed. In this case, the motor is doing less work, and there is less waste heat to dispose of.
A VFD can drive a motor faster than its nameplate speed, however, above the rated speed, the motor looses torque (twisting force). At higher speeds, less and less torque is possible. The maximum continuous power (speed times torque) is limited by the motor design, therefore a VFD cannot deliver more power than which the motor is thermally capable.
A VFD can also make a motor more efficient, but only at reduced load and/or reduced speed. A drive system will not use less power when the motor is running at rated speed and rated load. In fact, it uses slightly more due to the losses within the drive.
A VFD can make a motor reverse without the use of contactors, but it can’t make the reversal faster than the combination of the motor’s max torque and the load’s inertia allows.
A VFD can make a motor produce more than its rated torque but only briefly. The amount of time is limited by either the drive’s overload capacity or the motor’s thermal capacity. A drive cannot make a motor produce more than its maximum torque. Max torque or Stall Torque is generally not shown on the motor’s nameplate. The iron in the motor can only sustain a certain amount of magnetic flux density, even if iron is driven harder, the flux density will not go up. The amount of torque a motor creates at the flux limit is the most torque that can be achieved.
Motor Drive White Papers & Resources
Review all Invention House motor drive white papers and technical resources. Learn the facts about motor drives, how they work, how to properly set up a motor drive and troubleshoot your motor drive issues.