Abstract: Laboratory equipment with flammable refrigerant and connected to at least two different electrical potentials for supplying the equipment with electrical energy. An electrical switch arrangement has first and second switches for electrical separation from, respectively, the first and second potentials. A sequence controller switches on the first switch and thereafter the second switch. A monitoring device is connected via a first contact on the equipment side to the first switch and via a second contact on the mains side to an electrical potential other than the first electrical potential for detecting a switched-on state of the first switch and signaling the detection to the sequence controller. When the monitoring device signals a switched-on state, the sequence controller blocks operation of the equipment as a function of the signaled switched-on state and whether the first switch is expected to be switched on or switched off.

Abstract: A method and a device for monitoring the rotational speed of an element are disclosed. The element may be part of a centrifuge, e.g. a motor, drive shaft, or rotor of a laboratory centrifuge. The rotational speed of the element is not determined directly, but rather clock cycles are counted while the element rotates by a predetermined rotational angle. Exceeding a predetermined rotational speed is determined by comparing a number of counted cycles with a predetermined value. The method and device can be implemented in hardware without requiring a microcontroller with corresponding software, thereby eliminating a need to software certification.

Abstract: A method and a device for monitoring the rotational speed of an element are disclosed. The element may be part of a centrifuge, e.g. a motor, drive shaft, or rotor of a laboratory centrifuge. The rotational speed of the element is not determined directly, but rather clock cycles are counted while the element rotates by a predetermined rotational angle. Exceeding a predetermined rotational speed is determined by comparing a number of counted cycles with a predetermined value. The method and device can be implemented in hardware without requiring a microcontroller with corresponding software, thereby eliminating a need to software certification.