Siemens SINAMICS PERFECT HARMONY GH180 Operating Instructions Manual page 134

Glossary
Loss of signal feature
The loss of signal feature is a control scheme that gives the operator the ability to select one of
three possible actions in the event that the signal from an external sensor, configured to specify
the speed demand, is lost. Under this condition, the operator may program the drive (through
the system program) to (1) revert to a fixed, pre-programmed speed, (2) maintain the current
speed, or (3) perform a controlled (ramped) stop of the drive. By default, current speed is
maintained.
LVD
LVD is an acronym for Low Voltage Directive, a safety directive in the EU.
Lvl RH
This term refers the two security fields associated with each parameter of the system. These
fields allow the operator to individually customize specific security features for each menu
option (submenu, parameter, pick list, and function). These fields are shown in parameter
dumps and have the following meanings. Lvl is the term for the security level. Setting R=1 blocks
parameter change, and setting H=1 hides the menu option from view until the appropriate
access level has been activated.
Memory
Memory is the working storage area for the drive that is a collection of RAM chips.
Microprocessor
A microprocessor is a central processing unit (CPU) that exists on a single silicon chip. The
microprocessor board is the printed circuit board on which the microprocessor is mounted. The
drive employs a single-board computer with a Pentium® microprocessor.
NEMA 1 and NEMA 12
NEMA 1 is an enclosure rating in which no openings allow penetration of a 0.25-inch diameter
rod. NEMA 1 enclosures are intended for indoor use only. NEMA 12 is a more stringent NEMA
rating in which the cabinet is said to be "dust tight" (although it is still not advisable to use NEMA
12 in conductive dust atmospheres). The approximate equivalent IEC rating is IP52.
Normally closed (NC)
Normally closed refers to the contact of a relay that is closed when the coil is de-energized.
Normally open (NO)
Normally open refers to the contact of a relay that is open when the coil is de-energized.
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Type 6SR5 Air-Cooled
Operating Instructions, AK, A5E39390112