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Responding to Bill Sturm's query: It is normally connected to a two phase supply, where the phases are 90º of phase. Under certain conditions it can be connected to a single-phase source. The current lead arrangement is probably for the single-phase case. If interested in detail, please...

Responding to Dave McConnell's 14-Jul reply: If anyone wants to know how BP-Amoco resolved the problem of false alarms associated with the KIDDE "wire-based" H2 flame detection system, contact me directly. Regards, Phil Corso, PE Trip-A-Larm Corp Deerfield Beach, FL

Responding to R. Waddell's query: You didn't include application. If related to pipe-flange leak (and subsequent hydrogen flame detection) then contact BP-Amoco Instrument Dept at Whiting, IN Refinery. Or Bill Mostia on the List. Regards, Phil Corso, PE Trip-A-Larm Corp Deerfield...

Responding to David Leese's comment: If you were referring to operation of a 3-phase motor on a single-phase source, then, the capacitor is placed across the winding which is not directly connected to the source? If you truly meant a 2-phase motor (servo?), then, the capacitor is usually...

Ralph, neglecting the argument about expense, (yeah, I know about the most shouted phrase, SAFETY FIRST) the very scheme you suggest is what leads to the VERY COMMON practice of bypassing fire/gas alarm inputs. What about grounded inputs? Furthermore, what happens if the ground path is...

The "fire" could have been the result of a phenomenon called "arcing-ground-fault." It is caused by the inability of circuit protective devices to detect the fault-current level. It is evident by the appearance of spattered or melted metal, damaged enclosure materials, as well as badly charred...

The Physics of... "AC Induction (asynchronous in Europe) Squirrel-Cage Motors." Further to my 4-July reply on the subject, I apologize for the redundancy and superfluidity. The penultimate sentence should be replaced with: "... Thus, there is an increase in stator current corresponding...

In response to Sr. P. Moschetti's query and Guy Looney's reply: An AC induction (asynchronous) motor is a remarkable machine in its simplicity. But, that very simplicity is a result of a design compromise. High efficiency under normal operating conditions requires low rotor resistance. But...

Replying to Pete Talas' comments: I certainly laud you in updating the starting methodology. Regarding motor condition, you should be able to determine insulation condition by trending megger tests. On the other hand the motors are 40 years (+) old, and are probably close to their PLE. On...

What is the principle reason for VSD application to wound-rotor motor. Is it age of existing equip? or Soft-Start? or Variable speed? Phil Corso, PE Trip-A-Larm Corp (Deerfield Bch, FL)

To those of you requesting a copy of the mathematical analysis showing how single phase measurements can detect a "bad" terminal connection, please send me your Fax Number. Regards, Phil Corso, PE Trip-A-Larm Corp (Deerfield Bch, FL)

I know I promised an end to my comments on this thread, but following is a brief response to specific questions: When I referred to phase power factor sensitivity, I really meant the differences (from norm, from average, or from min/max values) of the per phase values of Amperes, Volts, Watts...

Honest, this is my last comment on the subject: Analysis revealed that the parameter most sensitive to contact resistance is phase power factor. Thus, make sure that the clamp-on Watt-meter can also provide a p.f. measurement. If interested in the mathematical analysis contact me. Phil...

How about heating (or cooling) the ball prior to attachment. Phil Corso, PE Trip-A-larm Corp

Some words of caution regarding generalizations: Power Circuits. Grounding both ends of a shield on motor feeders could affect ground-fault relaying. A circulation current will cause erratic operation in protection circuits that use zero-sequence CT's. Intrinsic Safety Circuits...

Updating earlier comments/suggestions to resolve Phil Dryburgh's problem: Rather than current averaging, I suggest the use of a single-phase clamp-on kW-meter. Measuring one phase at a time will yield more positive results. Single-phase power measurement is more sensitive to phase power...

In response to Vitor's response to Ricardo's response to Phil Dryburgh's request for help, this is what I talked about many months ago in my blurb about engineers who often "catch the mice, but let the elephant's go free." Having investigated several power feeder (both cable and bus duct)...

While using a cordless soldering-iron in an instrument rack room in a refinery, our tech was approached by a Safety Enforcer. They're easy to recognize in their red helmets and red coveralls. The enforcer insisted that the soldering-iron must be "grounded!" The tech obliged by wrapping one...

Further to my Fri, May 12, 2000, 12:00pm, reply to Phil Dryburgh: I ERRED AGAIN!. If a single connection is at fault, then, technically speaking, its phase will show a lower measurement than the unaffected phases. My reasoning is based on modeling the "poor" connection as a series resistor...