Laser Printer Start-up Surge

Transcription

1 Laser Printer Start-up Surge Page 1 f 8 Cntents Overview:... 1 Equipment and Test setup... 1 Inverters used in testing were:... 1 Laser printer used in test:... 2 Perfrmance Review:... 3 Summary... 7 Brther HL4020 laser printer specificatin:... 8 Overview: A custmer reprted that their 400 Watt (maximum pwer) rated laser printer was causing an verlad cnditin n a SSW inverter. Alng with this specific issue and a general issue f laser printers and surge prtectrs and UPS there have been verlads and failures f inverter mdels relating t laser printer applicatins. Laser printers surge when the units are pwered up and the fuser warms up. T characterize this fuser heater element surge this dcument recrds the current wave frms n a typical laser printer with several mdels f inverters and the grid. Equipment and Test setup Inverters used in testing were: SAM SSW SSW SA PST-150S-12 SB

2 Page 2 f 8 Laser printer used in test: Brther HL4020 with a maximum rating f 450 Watts. All measurements were taken with the fllwing equipment and settings unless therwise nted: Settings: Tektrnics TDS 2012 dual trace scillscpe, prbes with 1x setting. Tektrnics A622 AC/DC current prbe: 10 mv/amp. Tektrnics P5200 High Vltage Differential Vltage prbe 1/500 setting. The center line f the scillscpe screen is 0 Vlts. Vlts per divisin n screen captures are typically 200 r 100mV/divisin. 100mV/div with differential Vltage prbe = 50 V per divisin 200mV/div with differential Vltage prbe = 100 V per divisin Current per divisin scpe setting is typically 100mV/divisin. 100 mv/div with the current prbe = 10 Amps per divisin Channel 1: AC utput Vltage f the inverter (Yellw wavefrms) External Tektrnix Differential Vltage Prbe Mdel P5200; Attenuatin setting: 500 X (1/500) Oscillscpe prbe attenuatin: 1X (N attenuatin) E.g. Vlts per Divisin shwn in the screen 100 mv Effective Vlts per Divisin: 50 V (100 mv X 500 magnificatin = 50 V) Channel 2: AC utput current (Blue wave frm) External Tektrnix AC/DC Current Prbe Mdel A622 set at 10 mv per Amp Oscillscpe prbe attenuatin: 1X (N attenuatin) E.g. AC Amps per Divisin shwn n the screen 100 mv Effective Amps per Divisin: 10 A (100 mv/ divisin@10mv/amp=10) Fr Ipk t RMS cnversin Ipk * = Irms. Fr Watts Irms * 120 VAC was used.

3 Page 3 f 8 Perfrmance Review: The fllwing phtgraphs were recrded fr the grid and inverters. Pht 1: Grid with cld start. Channel 1: VAC (Yellw): Effective Vlts per Divisin= 100 VAC per Divisin= 20 Amps Hrizntal Scale 1 secnd Ipk=~55A Irms=38.9 Watt surge=4668 Pht 2: Grid with warm start. per Divisin= 10 Amps Hrizntal Scale 1 secnd Ipk=~34A Irms=24 Watt surge=2880 Nte: If printer cycled n and ff a cuple f times Ipk wuld lwer t ~30 amps as element was warmed.

4 Page 4 f 8 Pht 3: SAM start-up Channel 1 VAC (Yellw): Effective Vlts per Divisin= 100 VAC per Divisin= 20 Amps Hrizntal Scale 1/4 secnd Ipk=~55A Irms=38.9 Watt surge=4668 Nte: The SAM is a mdified sine inverter which is nt recmmended fr laser printers. warmed. Pht 4: SSW start-up Channel 1 VAC (Yellw): Effective Vlts per Divisin= 100 VAC per Divisin= 10 Amps Hrizntal Scale 1/4 secnd Ipk=~40A Irms=28.28 Watt surge=3394 Duratin f highest surge is ~50 msec.

5 Page 5 f 8 Pht 5: SSW NO-startup Channel 1 VAC (Yellw): Effective Vlts per Divisin= 100 VAC per Divisin= 10 Amps Hrizntal Scale 1/2 secnd Unit went int verlad cnditin. Pht 6: SA start-up Channel 1 VAC (Yellw): Effective Vlts per Divisin= 100 VAC per Divisin= 10 Amps Hrizntal Scale 1 secnd Ipk=~30A Irms=21.2 Watt surge=2545 Secnd surge nted 4.5 secnds after first start-up is the printer s mtr initializing. Peak Watts = 1700

6 Page 6 f 8 Pht 7: PST-150S-12 start-up per Divisin= 10 Amps Hrizntal Scale 1/2 secnd Ipk=~31A Irms=21.9 Watt surge=2628 PST inverter did emit a brief alarm n the printer s start-up. Pht 8: PST-150S-12 start-up, - extended time per Divisin= 10 Amps Hrizntal Scale 2.5 secnd Ipk=~34A Irms=24 Watt surge=2884 Lnger surge nted ~4 secnds after first surge is the printer s mtr initializing. Watts are = 1000 fr the duratin f < 4 secnds.

7 Page 7 f 8 Pht 9: SB start-up per Divisin= 20 Amps Hrizntal Scale 1/4 secnd Ipk=~48A Irms=34 Watt surge=4080 Summary It was nted n ne blg that sme laser manufactures d include a current limiter and/r thermistr in the fuser unit heater t keep the inrush current frm being s high, but this methd des slw dwn the heating up t perating temperature but we culd find n mdel with limiting shwn in the specficatins and the printer tested likely did nt have this feature. It has been shw that several f the 1500 Watt printers tested will start this particular maximum 450 Watt laser printer successfully. Sme f the inverters tested d prvide sme current limiting fr the printers shrt duratin surge as can be seen with the PST and SA in pht s # 6, 7, and 8, whether this current limiting is sufficient t prevent premature aging f the cmpnents has nt been determined. Therefre at this time if the characteristics f either device have nt been tested it wuld be recmmended that the inverter be sized fr the maximum pssible surge based n the printer s grid characteristics in pht # 1. In the case abve fr the HL4020 printer the inverters surge rating shuld be able t handle 6.5 times the maximum pwer f the printer, -surge rating f >4000 Watts.

8 Page 8 f 8 Brther HL4020 laser printer specificatin: