Standby / Emergency Power

Defects Probable causes for the defect Design for Maintainability (DfM) Guidelines
Generator: noise, vibe & overheating

Burnt fuse

  • Insufficient ventilation by radiator – water level is low or inadequate opening in the generator room.
  • Overloading or unbalanced load.
  • No acoustical control is provided.
  • Vibration isolator is ineffective due to improper mounting.
  • Vee belt is loose or too tight.
Design

  • Design mains failure standby power generation system as per code requirements.
  • Provide sufficient headroom (>2600mm) in generator rooms for maintenance tasks — i.e. sufficient height to
    enable any portion of the generating set or equipment to be raised freely for dismantling — as per SS 535:2007. (See also BS 7698-7:1996, ISO 8528-7:1994, NFPA 110:2016).
  • Comply with the general guidelines for earthing of generator sets and substations (BS 7430: 2011+A1:2015, SS 551:2009).
  • Adhere to the recommendations for daily diesel service tank package and tank storage (i.e. safety and suitability of design, emergency provisions, and minimisation of vapour hazard) as per SS 532:2016. (See also BS 5908-1:2012).

Construction

  • Conform to requirements for the construction, installation and testing of generator systems for buildings.
  • Provide sufficient access and clear passage for construction and maintenance.
  • Allotted spaces must be of sufficient strength or suitably strutted to support the loads (SS 535:2007, BS 7698-
    7:1996, ISO 8528- 7:1994, NFPA 110:2016).
  • Install indoor fuel tank with a level indicator that can be easily accessed for observation.
  • List and mark electrical wiring and equipment located near/within hazardous zones (i.e. day tank) (as defined by NFPA 70B [7] or IEC 60079) for installation in an appropriate manner (SS 532:2016, BS 5908-1:2012).

Maintenance

  • Practice proper housekeeping and avoid stacking and storing of combustible materials in the generator house.
  • Maintain records of preventive maintenance activities in a secure manner.
  • Conduct general inspections daily and check on fuel, lubrication and cooling systems.
  • Perform a monthly running of the generator on no load for half an hour.
  • Check battery charger, starting batteries and drive belt tension.
  • Adhere to the requirements for operation and maintenance of standby generator systems for buildings.
  • Once a year, run load test on the generator and check to ensure that emergency supply can support all essential emergency services (SS 535:2007, BS 7698-7:1996, ISO 8528-7:1994, NFPA 110:2016).
Dirty, leaky generator body
  • Filters are clogged and dirty.
  • Poor servicing – rusts should be removed and after that parts should be painted or lubricated.
Damaged generator insulation
  • Damaged during transportation and not checked before installation.
  • Frequent / extended operation at stand by rating.
  • Overheating is not detected through testing for a long time.
Upkeeping and safety issues of generator house

Combustible materials stored in generator house

  • Unsafe practices and no housekeeping rules for generator house.
No / delayed / less power supply

Charging batteries of generator

Failed connecting rod of diesel generator (Photo credit: Juarez et al., 2016)

  • Power source is not reliable or under capacity.
  • Wrong circuit design or wiring – it is unable to activate the generator or battery when the normal power supply is cut. Such control should be tested and marking on DBs are recommended to avoid ambiguity.
  • Generator fails to start automatically due to insufficient air intake for combustion, excessive corrosion or faulty limit switch.
  • Battery goes flat – over discharged or not charged properly, tampered, electrolyte condition not satisfactory.
  • Leakage in battery due to excessive rusting, poor cleaning or painting.
  • Poor contact at any junction or battery terminals – careless maintenance or rusting esp. in damp and dirty storage place.
  • Voltage-dip during transfer of power to alternate source if the transfer mechanism is faulty. UPS should be used for critical circuits.

References
[1]  

Normative References/Standards Referred to for Air Handling Unit and Fan Coil Unit