PTC THERMISTORS: YS4019, YS4020,YSM4021 g OVER-CURRENT PROTECTION DESCRIPTION: A range of three high voltage PTC thermistors. Types YS4019 & YS4020 have radial wires and a conformal coating type YSM4021 has a lead frame construction suitable for surface mount applications. FEATURES: Designed for over-current and over-voltage protection at voltages up to 1000V r.m.s. DIMENSIONS: Ability to withstand direct connection to 1000V r.m.s. supply YS4019 & YS4020 Suitable for resettable input protection of digital multimeters and other instrumentation Excellent stability Fail-safe operation Solid state High performance barium titanate ceramic OPTIONS: Non-standard resistances and tolerances Resistance matching Non-standard wire lengths Other wire configurations DATA: Bandoliered to IEC 286-2 with dimension Ho=160.5mm Tolerance on R .....................................20% 25 Maximum operating voltage............1000 r.m.s. Switch temperature T ........................8010C b YSM4021 Ambient temperature range: at maximum voltage.....................-20 to +60C at zero voltage ...........................-25 to +125C Lead wire material (YS4019 & YS4020) ..........................................Solder-coated copper Lead frame material (YS4021) ............................................Solder-coated brass Bandoliered to IEC 286-3 Dimensions in mm R Resistance -20 to +55C Residual current at 25C 25 Code mA YS4019 500 1000 max <3 YS4020 1100 2000 max <2 YSM4021 1100 2000 max <2 Crown Industrial Estate, Priorswood Road 808 US Highway 1 967 Windfall Road Taunton, Somerset TA2 8QY UK Edison, New Jersey 08817-4695 USA St Marys, Pennsylvania 15857-3397 USA Tel +44 (0) 1823 335200 Tel +1 (732) 287 2870 Tel +1 (814) 834 9140 Fax +44 (0) 1823 332637 Fax +1 (732) 287 8847 Fax +1 (814) 781 7969PTC THERMISTORS: YS4019, YS4020,YSM4021 OVER-CURRENT PROTECTION g DATA: INSTRUMENT PROTECTION SWITCHING TIMES: The input circuitry of digital multimeters Initial Maximum trip time (secs) and other instrumentation requires over- current mA current protection against the YS4020 & YS4019 YSM4021 unintentional fault conditions which can occur. PTC thermistors offer reliable, 50 25 convenient and cost-effective protection. 100 30 4.0 Solid state construction allows resettable 200 4.2 1.0 operation, eliminating the inconvenience 500 0.70 0.16 of fuse replacement. 1000 0.21 0.05 2500 0.1 Modern multimeters, with wide-ranging Thermistor connected to a 1000V r.m.s. supply via functions, are particularly at risk. The inad- a series resistance, adjusted to set the initial cur- vertent application of a voltage source to an instrument in resistance mode will cause rent. Switching time defined as the time required excessive currents within the input circuitry. for the current to reach 1/3 of the initial current at Multi-channel instruments, such as oscillo- an ambient temperature of 25C. scopes, are also susceptible if the ground terminals are raised to high potential. These CURRENT-VOLTAGE CHARACTERISTICS: high currents, if unchecked, would destroy the input circuitry. YS4019 The PTC thermistor is connected directly in series with the input terminals. It is chosen so that over the expected range of working conditions (current, voltage, ambient temperature) the device remains in a low resistance state, offering as little series resistance as possible to ensure accurate measurement. When a fault condition occurs, the abnormally 2 high current causes sufficient I R heating in the thermistor to switch it from low to high resistance, reducing the circuit current and preventing damage. YS4020 & YSM4021 After removal of the fault condition, the thermistor reverts to low resistance to re- establish normal operation. Devices can be chosen to achieve automatic reset (fault condition must be removed) or manual reset (power source disconnected). Crown Industrial Estate, Priorswood Road 808 US Highway 1 967 Windfall Road Taunton, Somerset TA2 8QY UK Edison, New Jersey 08817-4695 USA St Marys, Pennsylvania 15857-3397 USA Tel +44 (0) 1823 335200 Tel +1 (732) 287 2870 Tel +1 (814) 834 9140 Fax +44 (0) 1823 332637 Fax +1 (732) 287 8847 Fax +1 (814) 781 7969