Ieee std 1159-1995, ieee recommended Practice for Monitoring Electric Power Quality

 
3.1.48 precision:
Freedom from random error.
 
3.1.49 pulse:
An abrupt variation of short duration of a physical an electrical quantity followed by a rapid
return to the initial value.
 
3.1.50 random error:
Error that is not repeatable, i.e., noise or sensitivity to changing environmental factors. 
NOTEÑFor most measurements, the random error is small compared to the instrument tolerance.
 
3.1.51 sag: 
A decrease to between 0.1 and 0.9 pu in rms voltage or current at the power frequency for dura-
tions of 0.5 cycle to 1 min. Typical values are 0.1 to 0.9 pu.
b
 
See
: 
 
dip.

---

IEEE
Std 1159-1995
IEEE RECOMMENDED PRACTICE FOR
6
NOTEÑTo give a numerical value to a sag, the recommended usage is Òa sag to 20%,Ó which means that the line volt-
age is reduced down to 20% of the normal value, not reduced by 20%. Using the preposition ÒofÓ (as in Òa sag of 20%,Ó
or implied by Òa 20% sagÓ) is deprecated.
 
3.1.52 shield:
A conductive sheath (usually metallic) normally applied to instrumentation cables, over the
insulation of a conductor or conductors, for the purpose of providing means to reduce coupling between the
conductors so shielded and other conductors that may be susceptible to, or that may be generating unwanted
electrostatic or electromagnetic fields (noise).
c
 
3.1.53 shielding: 
The use of a conducting and/or ferromagnetic barrier between a potentially disturbing
noise source and sensitive circuitry. Shields are used to protect cables (data and power) and electronic cir-
cuits. They may be in the form of metal barriers, enclosures, or wrappings around source circuits and receiv-
ing circuits.
c