 and an overload relay which trips if the current in a traction motor's circuit exceeds 265 amps; tripping of these relays automatically reduces the train's acceleration.The engineer's instrument panel has warning lights which illuminate when any of these relays trip (except for the differential relay—its action can be deduced from certain peculiarities in the tripping of the circuit breaker), and the tripping of the wheelslip relay also activates a warning bell.To protect maintenance workers from electrocution, all high-voltage cabinets have safety switches which automatically lower the pantograph if the cabinet is opened while the power car is energized.