Specifications

Type SSM Specication Guide
Low Voltage Products & Systems 11
ABB Inc. • 888-385-1221 • www.abb.com/lowvoltage 1SXU132173M0201 [AC 1007.2] - 2/02
C) SCR Modules
1) PIV Ratings: SCRs will be connected as inverse parallel pairs in series circuits to attain the following Peak
Inverse Voltage ratings as a minimum for each phase:
System Voltage: 1500 / 2300V Pairs: 1 ; PIV Rating.; 6500V
System Voltage: 3300 / 4160V Series Pairs: 2 ; PIV Rating.;13000V
2) Protection: RC snubber network circuits on each phase assembly. To avoid possible component
damage, MOV protective devices shall be used only on the gate ring circuitry.
3) Efciency: 99.7% through SCRs, 99.97% in bypass mode.
4) Control Method: To ensure reliable gate ring even when powered with on-site generators, ring circuits
shall use individual phase transformer coupling method for maximum isolation and rapid rise of ring pulse.
5) Noise Immunity: The gate ring circuitry shall be protected from electrical noise and transients to ensure
reliable starting and ring of the SCRs under all power conditions, regardless of the available fault current
or motor lead length.
(a) They shall be amplied and isolated from the control voltages by means of rugged encapsulated ring
transformers that provide separate power sources for each set of SCR gate drives. The design shall
allow for a “back-porch” DC carry-over of the ring pulse to prevent the SCRs from falsely turning off
due to ringing of the output current or line notching caused by other connected equipment. The gate
drive shall be maintained for 240 electrical degrees from the zero cross point to avoid motor switching
transients.
(b) For additional reliability and to protect against EMI/RFI interface generated by the internal components,
connections to the Digital Control Unit shall be ber optic.
(c) When at all possible, the starter shall not require line reactors in the Medium Voltage power section.
Those that do shall include them within the same enclosure as the starter and shall be UL listed in this
conguration.
D) Ambient Conditions
1) Temperature: As a standard of unit design quality, starter shall be documented to show the design
has been tested for 0 – 50° C (-32 to 122° F) operation, and Overload Capacity shall be rated at this
temperature.
2) Altitude: 3300 ft (1000 m) maximum without derating.
3) Humidity: 0 – 95% RH, non-condensing.
4) Thermal: Heat sink temperature switches designed to trip at 85° C.
E) Electronics
1) Non-Volatile Memory will be used throughout the control and protection systems. To prevent the possibility
of loosing protection values, stored programs or statistical data, battery back-up memory systems will not
be allowed.
(a) The starter shall store all factory defaults in a preset replaceable EPROM memory chip.
(b) User Programming and statistical data shall be stored in EEPROM memory for ready alteration. Loss
of power shall not affect memory status.
(c) For fast updates and operation, running programs shall use DRAM memory. The starter shall store the
DRAM memory contents to the EEPROM upon power failure, and restore it upon return to normal.