Safety Systems Flashcards
define voltage
the power potential behind the electrical energy
higher the voltage difference = greater the current moves through object
define current
flow of electricity from a point of higher voltage to lower; measured in amperes (Amp); flow of electrons from negative to positive
current = voltage / resistance
> 100mA bad for heart; >120mA potentially fatal
harmful effects of current depend on
- amount
- path
- time length
amount of voltage can handle depends on
total resistance of the body
- body fat
- fluid intake
- skin sweatiness (skin resistance= 1megohm dry; 1 kilohm when wet)
- where contact made
effect of ground wire connection
ground wire is the path of least resistance; if wire became exposed any current passing from wire to device would travel easier through ground wire than H.C.W
micro-shock occurrence and standards
monitors, ventilators
<0.01 mA for patient interface
<0.1 mA for instrument chassis
define transducer
a device that transforms energy from one type to another; pressure/mechanical energy measured via strain gauge
define voltmeter
a device that measure voltage aka the amount of electrons available to supply an electrical system
define ohmmeter
a device used to measure electrical resistance
1 volt/1 amp = 1 Ohm
define ammeter
a device used to measure the strength of an electrical current in ampere (Amp)
1 amp = 6.25 x 10^18 electrons passing per second
define resistance
the property of a conductor that is influenced by the conductors specific chemical composition, length and cross sectional area; measured in Ohms; opposite of flow
resistance proportional to length of wire
resistance inversely proportional to cross sectional area
define fuse
device that opens the circuit by melting/breaking in the presence of increased current flow; must be replaced when “blows”
define circuit breaker
device that responds to current flow above the rated capacity by opening a switch and “breaking the circuit”; must be reset by moving the switch to the “on” position (reusable device)
define AC / DC current
Alternating Current: a current which flows continuously and reverses direction, usually in periodic fashion of 60 Hz (cycles/second) .. alternates pos to neg, then neg to pos
Direct Current: a current that flows continuously in the same direction. Used in stand-alone generators or batteries
define battery
device that converts chemical energy to electrical energy using an anode, a cathode, and an electrolyte solution/gel