we used a PTC for sensing the air temperature in the lamp compartment of a LCD projector. If the temperature in the compartment would rise too high, the PTC would force the controller to shut down the lamp power supply. The test house didn't accept the PTC, because it wasn't recognized in XGPU2 (thermistor type devices) and therefore considered unreliable. We had to perform a locked rotor test on the lamp compartment fan with the PTC bypassed. I was lucky that the projector passed the test, even with the PTC bypassed.
UL has a Practical Apllication Guideline No. 5.1:002 on NTC's used as fan speed controller. The requirement is that the NTC must be either recognized in XGPU2 or should meet a similar level of component requirements in an IEC standard. If the NTC isn't recognized, the product must pass the heating test with the device not actively controlling the fan, which means with the fan operating at the lowest air-flow rating. Another PAG (2.11:001) is for Limited Power Sources using PTC's to limit the output current. Here again the requirement is that the PTC should have been tested and certified. Regards, Jean-Marie Vandenbulcke EMC & Safety Manager Phone: + 32 56 368 331 Fax: + 32 56 368 355 mailto: [email protected] www.barco.com > -----Original Message----- > From: [email protected] > Sent: Wednesday, November 17, 1999 2:43 PM > To: [email protected] > Subject: PTCs for Transformer Overload/Short Circuit Protection > > > Hello Group, > > Anyone had problems with Test Houses regarding the use of PTCs in > Transformer Primary and/or Secondary Windings to Protect Against > Overload/Short Circuit Conditions? > > > Regards, > +++++++++++++++++++++++++++++++++++ > RTTE Directive Seminar > Renaissance Hotel, Tel-Aviv > 12th January 2000. For details: > http://www.itl.co.il/RTTE.htm > +++++++++++++++++++++++++++++++++++ > > > Peter Merguerian > Managing Director > Product Testing Division > I.T.L. (Product Testing) Ltd. > Hacharoshet 26, POB 211 > Or Yehuda 60251, Israel > > Tel: 972-3-5339022 Fax: 972-3-5339019 > e-mail: [email protected] > website: http://www.itl.co.il > > > > > > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to [email protected] > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to [email protected], > [email protected], [email protected], or > [email protected] (the list administrators). > --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
