Dear colleagues, please advise on the following: typical VFD cable has three symmetrical ground conductors. Can I combine these three ground conductors together and crimp all of them in a single larger compression lug? The site location is in the USA. Will this arrangement be acceptable. or this...
We order from Europe electrical equipment that complies with the following EU standards:
EMC Directive EN61326-1:2013
Low Voltage Directive EN61010-1:2010
Machinery Directive EN ISO 12100:2010
RoHS Directive EN50581:2012
CE Marking
The end user in USA specifically requires that the equipment...
We have a specification of PM synchronous motor driven by VFD. The motor spec requires external inductance about 20 microHenry. Our understanding was that this inductance is required to reduce dv/dt of PWM voltage pulses, thus reducing a stress applied to motor insulation, reducing accelerated...
We used to refer for inverter duty motor specifications to the standard NEMA MG1, part 31 (for US built motors) and IEC 60034-17 (for EU motors). The NEMA MG1 Part 31 applies only to squirrel cage induction motors. What document/standard (if any) would apply to inverter fed synchronous PM motors ?
Dear colleagues,
We consider application of VFD systems [range (300-700)HP] in the area El Monte, California.
Can anybody refer to EU VFD supplier that would provide seismic rated VFD cabinets?
Our equipment has to have UL listed/recognized components. Some of currently used components have been built to MIL standards. Do we still need to replace them with UL compliant parts, or MIL compliant parts could be acceptable? Is there any general consensus about that?
The VFD operates at 575V, fed by step-up drive isolation transformer 480/575V. Inside that VFD, there is a switching DC power supply (input power three phase, 400V) fed from a dedicated 400VA control transformer 575/400V. This power supply has failed (as we assume, the failure could be...
Please advise: for VFD system (unity PF at AFE) with PM synchronous motor - how to estimate total power/current consumed from the grid when the motor is spinning up to max speed with no shaft load.
We are analyzing a bearing failure on VFD driven PM motor. Motor MFG uses DE and NDE insulated bearings (brand AKN, Germany) and DE ground brush. These bearings have the outer ring surface coating (medium grey color). This seems to be either ceramic or aluminum oxide insulating provision...
This could be a very simple question, but after many years in electrical engineering I suddenly realized that can not determine voltage classification of the VFD system (enclosure) that has input voltage 575V AC and DC bus voltage 850 V DC. Is such equipment classification considered to be below...
Our customer initially ordered a VFD based test stand. Electrical dynamometer motors operate only in power absorbing mode. The 4-quadrant VFD (with PWM IGBT based front end) was expected to regenerate the shaft power (about 3 MW) back to the grid. The problem occurred when the customer failed to...
We received VFD with power entry cabinet that has ABB EMAX circuit breaker (5000A, 1000V). This is a fixed mounted MCB with motorized control and push buttons ON and OFF on the cabinet door. We feel that the MFG completely missed the OSHA requirement that the main disconnect device must have...
Please advise how to estimate a current consumed by VFD (front end)from the grid when spinning the motor (no-load). Motor magnetizing current is known. This is 4-quadrant VFD with AFE, DC bus and PWM inverter/converter. We understand that at no-load condition motor consumes reactive current...
Dear colleagues,
It is interesting to hear some opinions on the issue that seems to be confusing. Below is a quotation from NEC (2014 Edition):
430.122 Conductors — Minimum Size and Ampacity.
(A) Branch/Feeder Circuit Conductors. Circuit conductors
supplying power conversion equipment included...
Could anyone advise which reputable motor manufacturer (worldwide) has a capability to build inverter duty induction motor with the following major parameters: Rated Power 1000 HP, Rated Torque 3000 ft-lb, Base Speed 1750 RPM, Top speed 6000 RPM, Max voltage 690V? We've already got negative...
Please advise: are there any standards (in US) that govern internal wiring ampacity selection and protection for electronic enclosures (like 19" rack mounted industrial PC).
Please advise is there any governing document or standard in US (ANSI,IEEE,NEMA) that makes mandatory usage of key interlocking provisions for MV drives? Specific question: the separately (from drive) installed MCB must be key interlocked in OFF position allowing access to MV drive cabinets, or...
Please advise, whether the diesel-locomotive cable (DLO), say, 535 kcmil, 1 cond, can be used for industrial application and run in the open cable tray?
Dear colleagues,
Our company develops dynamometer systems. One of systems is based on a special liquid cooled motor. This motor is designed without terminal box, it has 3 power studs in the bottom part of the motor. We install this motor on a frame, that contains hydraulic cooling system. One of...
The VFD system (USA installation) has PWM Active Front End (AFE) and two motor inverters fed from the common DC bus. Inverter 1 is connected to 575V motor, therefore, the AFE input voltage is 575V (after step-up drive isolation transformer 480V/575V). The DC bus voltage is 900VDC. The Inverter 2...
