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Replying to Syed Zafar's Wed, Sep 26, 8:41 am, query: GENERAL INFORMATION Insulation resistance measurements, using a "Megger-type" instrument at 500 Volts (dc) or 3,000 Volts (dc), can provide accurate indication of the condition of 'new' insulation materials. The results are also meaningful...

Responding to Charlie Griswold's Sep 6, 9:40 am, reply: I apologize for misunderstanding your query. The use of a differential-gear won't solve the basic problem which is related to the torque-angle of one motor with respect to the other. Although the gear box solution compensates for different...

Responding to Brett Haas' comment: If the grounding conductor is in an intact metal conduit for mechanical protection, the conduit should preferably be of non-ferrous material. If the conuit is constructed of ferrous material, then both ends of the conduit must be bonded to the grounding...

Responding to Charlie Griswold's query dated Wed, Aug 29, 2001, 2:06 pm: I would not recommend the two motor configuration that you proposed, i.e., physical coupling to one load (ca 19 Hp). This position is based on the presumption that you are talking about AC induction (asynchronous) motors...

Information about distribution and utilization voltages can be found in the following sources: IN THE USA Standards covering the recommended nominal voltages can be found in ANSI C84.1-1989 covering 120 Volts to 230 kiloVolts. ANSI C92.2-1987 covers AC Electrical Systems and Equipment...

Responding to Don Pittendrigh's comment: I disagree. I can personally verify that an input fuse on the return is helpful, at least in two refinery SIS (ESD for the older, but wiser List members). In both events, trip input circuits were inadvertently exposed to higher voltage. The only...

Gray is the correct spelling, grey is not. The Gray-code is one of a number of cyclical digital codes in which successive numbers differ by just one bit. Cyclical-codes are prominent in two digital technique areas: analog-to-digital conversion; and digital communication error detection and...

The GRAY Code was discussed in grayt detail around Jan-Feb. Regards, Phil Corso, PE (Boca Raton, FL)

Responding to Graham Patten's query: Smallest switch (actually a pushbutton used to reset a DIN-rail mounted module) that I used was approximately 3 mm in diameter. It was manufactured by Wilbrecht Electronics Inc., in St. Paul, MN. However, because I couldn't get a sealed version, I switched...

Responding to Arvind Sharmar's query on the subject: An operating motor has a constant kVA characteristic. This means that if voltage drops then current will rise. Conversely, if voltage increases then current decreases. A voltage variation will also affect magnetizing current and slip (speed)...

Solid wires, below a certain size, are allowed by the NEC code (310-3). However, if there is the slightest hint of vibration exposure, especially where even slight movement is normal, for eample, at motor controller or relay terminals, I wouldn't hesitate to recommend stranded. In addition...

See 501-5. Regards, Phil Corso, PE (Boca Raton, FL)

It's been done! Regards, Phil Corso, PE (Boca Raton, FL)

How about hi-accuracy GPS. Regards, Phil Corso, PE (Boca Raton, FL)

Jiri, But, did use Excel? BTW, there is a legitimate quest to determine if all numbers in base 10 can become palindromes. The procedure is simple enough... 1) Pick a number. 2) Reverse the digit order and add it to the original. 3) Repeat with the number obtained in 2) 4) Keep repeating...

Responding to John Mangoff's and Zan Von Flue's queries: As the inventor of the only truly "virtual" digital signal conditioner, i.e., detection and diagnosis of open-circuits, short-circuits, and ground-faults on switched devices, I of course, would prefer the hardware approach. This...

Correction to my Thu, Jul 12, 2:53pm post on the subject. I inadvertently interchanged Fp and Fo. The correct notation should be: Fp = 2(n+1) and Fo = 2n. Optimistic Case The lower and upper MTBF values at a 90% confidence level are 475 hrs and 3,670 hrs, respectively. Pessimistic...

As others have already advised, there will be a myriad number of solutions. However, I will attempt to provide you with a starting point... simply because engineers love numbers. You're problem is not unique. Usually one tests a new model to its initial failure, fixes it, tests to the second...

As promised in my Thu, Jul 5, 3:28pm, response on the subject: The document that lists typical inertia data for USA manufactured motors is: NEMA Standards Publication MG-1993. Regards, Phil Corso, PE (Boca Raton, FL)

The use of a capacitor, permanently in parallel with the motor terminals will produce a braking torque. However, I am unaware of a tried and true sizing calculation. Trial and error will be necessary. The capacitor can be sized using the technique for power-factor correction. However, the...