Vital relays have been a mainstay for switch machine control in the field. While they have established an enviable history of reliable performance, vital relays require periodic maintenance for this degree of reliability to be achieved. US&S has developed a cost-effective yet equally reliable alternative for low-voltage switch machine control applications: The SML-24 Switch Lock and its companion module, the SMC controller.
Each SML-24 allows for control of up to two switch machines simultaneously. The maximum current capacity of the SML, which functions as a DC/DC converter, is capable of driving one stalled and one operating switch machine at the same time. Each SMC can control one switch machine. The SMC is designed to interface with 2, 3, or 5-wire control switch machines and solid-state vital wayside controllers, such as the US&S MicroLok II and E-Code systems, as well as equivalent non-US&S systems. The SML and SMC units allow replacement of vital switch control relays, such as lock and overload.
The SML-24 uses both 24 Vdc and 12 Vdc power sources and a 12 volt "Lock" gating signal. The NW (normal) and RW (reverse) request signals are applied to the SMC unit. When the SML-24 outputs the lock signal, it enables the SML to output 24 Vdc at a maximum current of approximately 35 amps to drive lowvoltage switch machines.
A thermal switch protects the SML unit from overheating by shutting it down until the temperature is reduced to an acceptable level, at which time the switch resets itself. A Power LED on the front of the unit indicates when the output voltage is present. Any short circuit on the SML output will cause the LED to go dark.
 View Product Sheet PDF for more information
Back to the top
|
