MONITORING RAPID VOLTAGE FLUCTUATIONS AND HARMONICS DUE TO OSCILLATOR AND RELAYS IN THE CORD CONNECTING THE EQUIPMENT TO MAINS SUPPLY
Abstract
Dealing with the precompliance EMC emissions testing for a new fluxgate magnetometer, in order to comply with European norms EN 55022, we experienced some difficulties, three of them being addressed in this paper: a) Best compromise for the mains filter; operating with an own manufactured V-LISN and a pair of 1:1 high quality transformers, the dominant component (common or differential mode conducted emissions) could be identified. Determining the major component of the conducted emission, allow us to decide which element of the filter should be modified to achieve the better compromise “size versus reduction in the total emission”; b) Best decoupling option for the electromechanical relays, mainly involved in the power management scheme and in the auto-ranging function; c) Minimising the spectral energy at harmonics of the fundamental frequency of the oscillator with the switching power supply; by reducing the magnitude of the open loop gain (was utilized a capacitive divider), the feedback current was also decreased, with the immediate result of an improvement in the spectral envelope of the power supply current.
Event details
- Event
- TC4 Symposium 2001
- Technical Committee
- TC4
- Place
- Lisbon, PORTUGAL
- Time
- 13 September 2001 - 14 September 2001