01/01/2008 - Volume IV - Issue I

Siprotec 7SJ62 - an ideal retrofit for SAMMS motor management relay


The SAMMS (Siemens Advanced Motor Master System) unit is a microprocessor based device designed to provide complete control and protection for low-voltage or medium-voltage motors. The SAMMS unit is also a dedicated logic controller programmable for all common starter configurations.


With a large number of customers still using the out-of-production SAMMS, Siemens offers the SIPROTEC 7SJ62 as a direct replacement solution. The SIPROTEC 7SJ62 offers protection and control for a wide range of motor applications, ranging from low-voltage to medium-voltage and small to very high horsepower rating.


The SIPROTEC 7SJ62 is a microprocessor device which can provide all the protection and control needs to retrofit SAMMS units. The same 7SJ62 is capable of retrofitting both SAMMS-MVE and SAMMS-MVX. The continuous function chart capability[CFC] of the SIPROTEC family offers the logic programming using the universally accepted logical Boolean gates, i.e. AND, OR etc.


Protection settings offered by 7SJ62 surpass the available protections for either SAMMS-MVE or SAMMS-MVX.


Up to four pushbuttons can be realized via the function keys of the 7SJ62, while the motor start and stop commands are realized using front panel commands.


The major advantages of 7SJ62 are:

  • Oscillographic recording

  • Event reporting

  • Industry standard communication protocol

  • Ease of parameterization with user friendly GUI, DIGSI

  • Up to four different setting groups.

Seven programmable LEDs, Self-test LED, Run LED, front communication RS-232 port, and bright four line LCD display are amongst the many features makes the Siemens 7SJ62 an ideal retrofit solution for SAMMS-MV units.


SIPROTEC 7SJ62 functional overview


Circuit Protection:

  • Time-overcurrent protection

  • Neutral fault protection

  • Ground fault protection

  • Overload protection

  • Undercurrent monitoring, loss of load

  • Starting time supervision

  • Restart inhibit

  • Locked rotor

  • Temperature protection

  • Phase sequence monitoring

  • Breaker failure protection

  • Negative-sequence protection

  • Cold load pickup

  • Phase-sequence monitoring

  • Under voltage protection

  • Over voltage protection

  • Displacement voltage

  • Frequency protection.

Control Functions:

  • Ladder logic can be realized using CFC

  • Commands and control of breakers and contactors

  • Control via keypad, digital inputs, DIGSI 4, or SCADA system.

Monitoring Functions:

  • Operational measured currents (la, lb, lc, ln, or lGnd)

  • Operational measured voltages (Vab, Vbc and Vca or Van, Vbn, and Vcn)

  • Power measurement (P,Q,S)

  • Energy metering values (Wp+, Wp-,Wq+, Wq-)

  • Circuit-breaker wear monitoring

  • Trip circuit supervision

  • Communication connection supervision.

Communication Interfaces:

  • System interface---MODBUS RTU---DNP 3.0---PROFIBUS DP / IEC 60870

  • Service interface for DIGSI 4

  • Front interface for DIGSI 4

  • Time Synchronization via IRIG B / DCF77.