EMI Limits for LA Metro Light Rail Lines

The Los Angeles County Metropolitan Transportation Authority (LA Metro) operates a fleet of 171 light rail vehicles, with dc thyristor chopper, GTO inverter, and IGBT inverter propulsion systems on its existing and new light rail vehicle (LRV) lines. LA Metro performed a program to set consistent and meaningful standards for train emissions and train control equipment immunity for existing trains, signal equipment, and future rolling stock and train control systems. The project team surveyed and analyzed existing LA Metro LRV signal systems to determine the electromagnetic interference (EMI) susceptibility to LRV conducted and inductive emissions for each line. The measured susceptibility curves are the quantified basis for conducted and inductive emission limits which provide adequate protection for signal equipment from LRV emissions on existing and future lines. Inadequate protection results in intermittent or sustained signal disruptions causing delay or hazards. Excessive protection adds weight and cost to the LRVs and provides no benefit to LA Metro and its passengers.