A safety relay comprising a first switch , a second switch , a first controller , a second controller , a pulse-width modulation, PWM, sensing circuit , and a coil ; wherein the first switch is connectable to a power source ; wherein the second switch is connected between the first switch and a first connection of the coil of normally open contacts ; wherein the first controller is connected to the first switch for controlling the first switch with a first output signal comprising one of a close signal for closing the first switch and a first PWM signal with a first duty cycle for opening and closing the first switch on each PWM cycle; wherein the second controller is connected to the second switch for controlling the second switch with a second output signal comprising one of a close signal for closing the second switch and a second PWM signal with a second duty cycle for opening and closing the second switch on each PWM cycle, the first duty cycle being different from the second duty cycle; wherein the PWM sensing circuit is connected to a second connection of the coil for sending a sensed PWM signal to an input of the first controller and an input of the second controller ; wherein the first controller is configured to send the first PWM signal while the second controller is configured to send a close signal and wherein the second controller is configured to send the second PWM signal while the first controller is configured to send a close signal; and wherein the first controller is configured to verify that the received PWM signal matches the first PWM signal while sending the first PWM signal and the second controller is configured to verify that the received PWM signal matches the second PWM signal while sending the second PWM signal. wherein the first switch is connectable to a power source ; wherein the second switch is connected between the first switch and a first connection of the coil of normally open contacts ; wherein the first controller is connected to the first switch for controlling the first switch with a first output signal comprising one of a close signal for closing the first switch and a first PWM signal with a first duty cycle for opening and closing the first switch on each PWM cycle; wherein the second controller is connected to the second switch for controlling the second switch with a second output signal comprising one of a close signal for closing the second switch and a second PWM signal with a second duty cycle for opening and closing the second switch on each PWM cycle, the first duty cycle being different from the second duty cycle; wherein the PWM sensing circuit is connected to a second connection of the coil for sending a sensed PWM signal to an input of the first controller and an input of the second controller ; wherein the first controller is configured to send the first PWM signal while the second controller is configured to send a close signal and wherein the second controller is configured to send the second PWM signal while the first controller is configured to send a close signal; and wherein the first controller is configured to verify that the received PWM signal matches the first PWM signal while sending the first PWM signal and the second controller is configured to verify that the received PWM signal matches the second PWM signal while sending the second PWM signal. <EOS>