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A negative temperature coefficient or NTC resistor has a relatively high resistance when it is cold, but almost no resistance at high temperatures.

Open frame power supplies have no housing and are designed to comply with protection class IP00.

An optocoupler is a component that consists of a photodiode (LED) and an electrically isolated phototransistor. It transmits signals and is often used for galvanic isolation in the control circuit of power supplies.

OVP or overvoltage protection refers to a protection circuit that restricts the output voltage to a predefined maximum value.

Parallel mode distributes the current equally between power supplies that are connected in parallel. In parallel mode, the output voltage is regulated so that at no load it is around 5% higher than at nominal load.

The power factor or cos phi of a power supply is the ratio between the real power and the apparent power.

The reliability and availability of the DC voltage can be increased with the help of a redundant system. To create a redundant system, an additional power supply must be installed in reserve. This power supply then provides the necessary load current if another power supply in the system fails.

The IEC/EN 61140 standard classifies electrical equipment according to its safety with regard to shock currents and electric shocks.

A shutdown input is a signal input that allows a power supply to be shut down by means of an externally supplied voltage or a simple switch. A shutdown input is galvanically isolated from the input voltage and can be supplied by separated extra-low voltage (SELV) circuits.

A surge is a transient voltage (e.g. on the mains power line) caused by nearby lightning strikes or inductive voltage spikes after a circuit breaker has been triggered by a short circuit.

All PULS power supplies have outputs that are overload-proof, short-circuit-proof and no-load-proof. No external fuse is required on the output to protect the power supply.

Overshoot is the amount by which the output voltage exceeds its static value when there is a rapid change in the load or in the input voltage or when the input voltage is connected.

Overtemperature protection causes an emergency shutdown. It prevents thermal damage being caused to a switch-mode power supply or a failure of isolation as a result of excessively high temperatures.

The ambient temperature is the air input temperature two centimetres below the power supply.

A UPS or uninterruptible power supply is a power supply with VRLA batteries or capacitor storage that can supply the connected devices with power for a specific period in the event of a power failure.