1.2.1 The SAMMS-LV Device Models
The SAMMS-LV device is available in two models: SAMMS-LVE and SAMMS-LVX. Each model meets the various demands of industrial and commercial specifications and installations. Table 1.2 compares the features of each model.
The SAMMS-LV device is designed for critical process control where prevention of downtime is critical. It offers motor control and protection along with motor diagnostic and motor/driven equipment protection. Engineering and operating personnel have access to important data enabling them to optimize motor-driven equipment capabilities, maximize the process system output and facilitate maintenance.
SAMMS-LVX is a full function model, applicable to all control needs, from a simple across-the-line unit to a more compli- cated reduced voltage scheme. It includes all of the functions listed in table 3.7. Any of the standard control circuits listed in table 3.3, or a custom circuit, may be downloaded. The SAMMS-LVX device accepts up to four remote inputs, while SAMMS-LVE accepts two remote inputs.
SAMMS-LVE is a model of SAMMS-LV tailored to across-the- line (FVNR) applications. It provides all of the protective func- tions of the SAMMS-LVX device, except that it has no jam
protection (F23), loss of load protection/alarm (F24), or process current warning (F22) functions. Functions F3 and F5 associ- ated with two-speed applications are not available. No provi- sion for automatic reset (F8) is provided. SAMMS-LVE accepts two remote inputs, and provides one output to actuate a single contactor. An alarm contact is not available with SAMMS-LVE.
The SAMMS remote inputs are compatible with all PLCs and electromechanical remote control devices that have a 120VAC or 125VDC output signal.
1.2.2 Advanced Protection for Low-Voltage Motors
For advanced protection of low voltage motors, the SAMMS-LV device uses a motor model algorithm that continually calculates the stator winding and housing temperature as a function of the motor rms current. The motor model compares the calculated temperature to trip temperature values and provides a signal that trips the motor off line when the motor reaches a trip temperature value. The model closely emulates the heating and cooling of the motor windings and provides protection against both transient and steady-state overload conditions.
