Siemens SAMMS-MV 1.2.1 The SAMMS-MV Device Models, 1.2.2 Advanced Protection for Medium-Voltage Motors

1 Introduction

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 forMedium-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.