I.S. EN 50091-1:1993

1 General
  1.1 Scope
  1.2 Definitions
  1.3 General requirements
  1.4 General conditions for tests
  1.5 Components
  1.6 Power interface
  1.7 Marking and instructions
2 Fundamental design requirements
  2.1 Protection against electric shock and energy
       hazards
  2.2 Insulation
  2.3 Safety Extra-Low Voltage (SELV) circuits
  2.4 Limited current circuits
  2.5 Provisions for protective earthing
  2.6 AC and DC power isolation
  2.7 Overcurrent and earth fault protection
  2.8 Protection of personnel. Safety interlocks
  2.9 Clearances, creepage distances and distances
       through insulation
  2.10 External signalling circuits
  2.11 Limited power source
  2.12 Protection of the applied load
3 Wiring, connections and supply
  3.1 General
  3.2 Connection to power
  3.3 Wiring terminals for external power conductors
4 Physical requirements
  4.1 Stability and mechanical hazards
  4.2 Mechanical strength and stress relief
  4.3 Construction details
  4.4 Resistance to fire
  4.5 Battery location
5 Thermal and electrical requirements
  5.1 Heating
  5.2 Earth leakage current
  5.3 Electric strength
  5.4 Abnormal operating and fault conditions
Annex A: Test for resistance to heat and fire (normative)
Annex B: Motor test under abnormal conditions (normative)
Annex C: Transformers (normative)
Annex D: Measuring instrument for earth leakage current
         test (normative)
Annex E: Temperature rise of a winding (normative)
Annex F: Measurement of creepage distances and clearances
         (normative)
Annex G: Earth leakage current for equipment intended to be
         connected directly to IT power systems (normative)
Annex H: Guidance on protection against ingress of water
         and foreign objects (informative)
Annex J: Table of electrochemical potentials (informative)
Annex K: Thermal controls (normative)
Annex L: Backfeed protection test (normative)
Annex M: Examples of normal load conditions (normative)
Annex N: Ventilation of battery compartments (normative)
Annex P: Normative reference to International Publications
         (normative)
Annex Q: A-Deviations (informative)

Applies to electronic indirect a.c. convertor systems with electrical energy storage means in the d.c. link. The primary function of the uninterruptible power system (UPS) covered by this standard is to ensure continuity of an alternating power source.