{"id":11134,"date":"2016-10-03T18:05:54","date_gmt":"2016-10-03T16:05:54","guid":{"rendered":"https:\/\/mag.ebmpapst.com\/en\/?p=11134"},"modified":"2024-03-12T17:56:10","modified_gmt":"2024-03-12T16:56:10","slug":"residual-circuit-breaker-fault-currents-waveform-is-crucial-pfc","status":"publish","type":"post","link":"https:\/\/mag.ebmpapst.com\/en\/insights\/residual-circuit-breaker-fault-currents-waveform-is-crucial-pfc_11134\/","title":{"rendered":"The formula for the residual circuit breaker"},"content":{"rendered":"
\"helmut_lipp_ebm-papst\"

Helmut Lipp, R&D Manager Devel\u00adop\u00adment Elec\u00adtronics at ebm-papst in Mulfingen<\/p><\/div><\/div>\n

Fault currents can be dangerous for people, machinery and entire systems. For personal safety, Type A residual current circuit breakers with a maximum trip\u00adping current of 10 mA or 30 mA are required. Type B with 300 mA is required for fire safety, but such high currents can lead to irre\u00adversible harm or even death in humans, so the choice in indus\u00adtrial settings is not always easy.<\/p>\n

This is also an issue when elec\u00adtron\u00adi\u00adcally commu\u00adtated (EC) DC motors are used. For EC devices with passive power factor correc\u00adtion (PFC), Type A serves its purpose reli\u00adably. However, if for example EC fans are oper\u00adated in parallel, active PFC is used to avoid harmonic currents in the power grid. To decide which circuit breaker is the right one here, the topology of the commu\u00adta\u00adtion elec\u00adtronics needs a closer look since it deter\u00admines the current wave\u00adform in the event of a fault. Depending on the DC link voltage CZWK across the capac\u00aditor, a voltage builds up between the posi\u00adtive terminal of the capac\u00aditor and the PE poten\u00adtial; this voltage has a wave\u00adform that differs with the topology.<\/p>\n

With active PFC, the DC link voltage CZWK<\/sub> across the capac\u00aditor can be set to values of UZWK<\/sub> > \u221a 2\u00d7Uac,rms<\/sub>. Here the voltage poten\u00adtial is always greater than 0 V. The minimum value is Umin<\/sub> = UZWK<\/sub> -\u221a 2\u00d7Uac,rms<\/sub>. If there is an insu\u00adla\u00adtion fault, this is the same condi\u00adtion as if a resistor were inserted between the poten\u00adtial UZWK+<\/sub> and PE. The fault current behaves anal\u00ado\u00adgously to the voltage.<\/p>\n

For an inverter with active PFC, the current drops to a minimum value Ifault<\/sub> = \u221a 2\u00d7 UZWKmin<\/sub>\/Rfault<\/sub>. We have measured the behavior of the circuit topology, taking an insu\u00adla\u00adtion fault into account; a fault current Ifault > 30 mA was set. With this fault current, the Type A residual current circuit breaker did not trip.<\/p>\n

In the same exper\u00adi\u00adment using a Type B circuit breaker, it discon\u00adnected the circuit from the power supply at a time T2 after the fault occurred. In order to provide the neces\u00adsary safety for people, machinery and systems with EC drives connected to circuits using elec\u00adtronics with active PFC as boost converter, these residual current circuit breakers Type B are the right choice.<\/p>\n

\"ec-motor-aktive_pfc_1\"

EC motor with active PFC. The Type A residual current circuit breaker fails to trigger.<\/p><\/div><\/div>

\"ec-motor-aktive_pfc_2\"

The Type B residual current circuit breaker discon\u00adnects the circuit from the power supply at a time T2 after the fault occurred.<\/p><\/div><\/div><\/div>\n","protected":false},"excerpt":{"rendered":"

Fault currents can be dangerous for people, machinery and entire systems. For personal safety, Type A residual current circuit breakers with a maximum trip\u00adping current of 10 mA or 30 mA are required. Type B with 300 mA is required for fire safety, but such high currents can lead to irre\u00adversible harm or even death [\u2026]<\/p>\n","protected":false},"author":12,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"wp_typography_post_enhancements_disabled":false,"footnotes":""},"categories":[4,20],"tags":[123],"class_list":["post-11134","post","type-post","status-publish","format-standard","hentry","category-insights","category-motors","tag-ec-technology"],"acf":[],"_links":{"self":[{"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/posts\/11134","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/users\/12"}],"replies":[{"embeddable":true,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/comments?post=11134"}],"version-history":[{"count":1,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/posts\/11134\/revisions"}],"predecessor-version":[{"id":18694,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/posts\/11134\/revisions\/18694"}],"wp:attachment":[{"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/media?parent=11134"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/categories?post=11134"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/tags?post=11134"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}