Voltage supply control system for e.g. air conditioning appts. - uses relays operated with predetermined delays when voltage limits are exceeded

摘要

The supply voltage is controlled with predetermined delays to be switched when the voltage goes outside upper and lower limit values. An alternating mains supply is connected to an air conditioning compressor via a control system. This comprises a relay whose contacts cut the supply when it exceeds a max. value. A second relay has contacts which operate when a min. predetermined value is reached. A third relay has contacts which cut the supply when it falls below a third predetermined value for a predetermined delay period. This value is equal to or greater than the min. value and takes account of the starting current to avoid breaking the compressor circuit. A reset circuit re-establishes connectios after a delay period when the supply returns to normal.