Siemens user manual SAMMS-MV Device Models, Advanced Protection for Medium-Voltage Motors

1 Introduction

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Figure 1.1 SAMMS-MV, front view

1.2.1 The SAMMS-MV Device Models

The SAMMS-MV device is available in two models: SAMMS-MVE and SAMMS-MVX. Each model meets the various demands of industrial and commercial specifications and installations. Table 1.2 compares the features of each model.

The SAMMS-MV 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-MVX 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-MVX device accepts up to four remote inputs, while SAMMS-MVE accepts two remote inputs.

SAMMS-MVE is a model of SAMMS-MV tailored to across-the- line (FVNR) applications. It provides all of the protective func- tions of the SAMMS-MVX 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-MVE accepts one remote input, and provides one output to actuate a single contactor. An alarm contact is not available with SAMMS-MVE.

These remote inputs are compatible with all PLCs and electro- mechanical remote control devices that have a 120VAC or 125VDC input signal.

1.2.2 Advanced Protection for Medium-Voltage Motors

For advanced protection of medium voltage motors, the SAMMS-MV device uses a motor model algorithm that continu- ally calculates the stator winding and housing temperature as well as the rotor temperature as a function of the motor rms current. The motor model compares the calculated tempera- ture 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 as well as the rotor and provides protection against both transient and steady-state overload conditions.

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