Basic short-circuit current calculation
Dec 1, 1997, John A. DeDad
A basic electrical theorem says the amount of current that will flow through a short circuit depends on two variable values: The system voltage and the...
Understanding variable speed drives
Apr 1, 1997, Turkel, Solomon S.
A thorough understanding of how to match the VFD to the driven load is the key to a successful application.When applied properly, the variable frequency...
The basics of electrical troubleshooting. (part 2)
Nov 1, 1996,
Typical problem areas with CPTs include open circuits, partial shorts, complete shorts, and grounded windings. Your first check should be at the primary...
The basics of electrical troubleshooting
Oct 1, 1996,
We're talking about line-to-ground faults that may damage equipment. The NEC, per Sec. 215-10, requires that ground-fault protection for equipment (GFPE)...
The basics of insulation resistance
Sep 1, 1996, DeDad, John A.
One of the most fundamental of electrical installation and maintenance tasks is taking insulation resistance (JR) readings. This is done to verify the...
Sizing continuously loaded conductors made simple.
Aug 1, 1996, Hartwell, Frederic P.
Given a calculated load that is at least partially continuous, this updated four-part test assures that the conductors are correctly chosen.Selecting...
Sizing a circuit breaker.
May 1, 1996, Pauley, Jim; Young, Sandi
Circuit breakers are designed to carry 100% of their rated current while the NEC dictates an 80% application. Why the difference?One of the most often...
The basics of molded case circuit breakers.
May 1, 1996,
The traditional molded-case circuit breaker uses electromechanical (thermal magnetic) trip units that may be fixed or interchangeable. An MCCB provides...
The basics of capacitance.
Apr 1, 1996,
If we take two metal plates, separate them with a dielectric (insulator), and apply a DC voltage between the plates, current will not be able to cross...
The basics of transformers. (part 5)
Mar 1, 1996, DeDad, John A.
Precise lead or terminal designation is very important. There are specific parameters affected by terminal markings and coil relationships, and how we...
Understanding IG wiring
Feb 1, 1996, Lewis, Warren H.
The risk/benefit situation of SG and IG wiring methods has many variables, all depending upon the specific application and situation.There's plenty of...
Understanding PLC networks
Jan 1, 1996,
Knowing the available PLC network options and their best applications will ensure an efficient and flexible control system design.The programmable logic...
Understanding high performance UTP cable
Jan 1, 1996, Knisley, Joseph R.
Contractors and users now have a valid reference for pass/fail criteria when field testing installed data/communications cabling.Installers and users...
Understanding IG receptacles
Jan 1, 1996, Lewis, Warren H.
IG-style wiring is interesting because it's so unpredictable, from the standpoint of what it does and doesn't do. It may or may not be a good thing at...
Understanding insulation resistance testing
Jan 1, 1996,
How is IR testing done, in view of the fact that at least 80% of electrical maintenance and testing involves evaluating insulation integrity?Insulation...
