The operating temperature is the range of ambient temperature within which a power supply, or any other electrical equipment, operate in. This ranges from a minimum operating temperature, to a peak or maximum operating temperature, outside which, the power supply may fail.
Ingress Protection rating (or just IP rating), is an international standard (IEC 60529) used to rate the degree of protection or sealing effectiveness in electrical enclosures against intrusion of objects, water, dust or accidental contact. It corresponds to the European standard EN 60529.
An encoder is classified into four types: mechanical, optical, magnetic, and electromagnetic induction types.
Pulses per revolution (or PPR) is a parameter associated with encoders. Basically, it is a measure of the number of pulses per full revolution or turn of the encoder, with a full revolution being 360 degrees. In essence, it is a measure of an encoder's resolution.