NT255 電動(dòng)機(jī)保護(hù)器實(shí)現(xiàn)的功能主要包括：三相電流顯示、聲音報(bào)警、故障脫扣、故障記憶、過(guò)載保護(hù)、短路保護(hù)、漏電保護(hù)、缺相保護(hù)、相失衡保護(hù)、相序保護(hù)、過(guò)欠壓保護(hù)等。用傳統(tǒng)的模擬線路要實(shí)現(xiàn)如此綜合的功能，其線路將會(huì)變得非常復(fù)雜，整個(gè)裝置的體積也會(huì)非常龐大。目前一些模擬電子式電動(dòng)機(jī)保護(hù)器能實(shí)現(xiàn)的功能都比較單一，例如：過(guò)流保護(hù)器、缺相保護(hù)器、漏電保護(hù)器等，而單片機(jī)的出現(xiàn)，使得電動(dòng)機(jī)保護(hù)器的發(fā)展有了質(zhì)的飛躍，在智能化、功能多樣化、小型化、模塊化、性能可靠性等方面達(dá)到前所未有的水平。

NT255 用單片機(jī)系統(tǒng)實(shí)現(xiàn)電動(dòng)機(jī)保護(hù)的功能，在硬件方面主要由三相電流信號(hào)采樣、漏電流采樣、電壓信號(hào)采樣、鍵盤接口、顯示部分、控制輸出、報(bào)警輸出、通信接口等幾部分構(gòu)成。

硬件系統(tǒng)基本工作原理是：由電流、電壓互感器實(shí)時(shí)檢測(cè)電動(dòng)機(jī)的三相線電壓和線電流，并經(jīng)信號(hào)調(diào)理電路轉(zhuǎn)換后輸入單片機(jī)A/D轉(zhuǎn)換器的模擬輸入通道，根據(jù)算法，計(jì)算出信號(hào)的有效值，將計(jì)算出來(lái)的信號(hào)有效值與預(yù)先設(shè)定的相應(yīng)整定值進(jìn)行比較判斷，若在時(shí)限內(nèi)，采樣到的信號(hào)有效值都在設(shè)定的故障范圍值之內(nèi)，則認(rèn)為有故障產(chǎn)生，并由單片機(jī)發(fā)出故障控制信號(hào)對(duì)電動(dòng)機(jī)進(jìn)行跳閘斷電和報(bào)警。若無(wú)故障產(chǎn)生，則循環(huán)采樣、顯示和存儲(chǔ)電壓、電流信號(hào)。

NT255 

RADVISION MCU-323/20 CONFERENCING UNIT MCU-323

LAMBDA POWER SUPPLY ULTRAFLEX SERIES 400 WATT UAZ1JP

XSUNX NA2-16P AREA SENSOR

Moeller Easy 719-DC-RC with Easy 202-RE EASY719-DC-RC 

SPECTRA-PHYSICS EXCELSIOR-PS SPECTRA PHYSICS EXCELSIOR-

Siemens S42024-D5004-A100-4 IPU16 S42024-D5004

Siemens S42024-D5008-A201-01 OIS1D 1550nm S42024-D5008

Siemens S42024-D5001-A200-6 EI2-42 120 Ohm S42024-D5001

Siemens S42024-D5013-A100-7 SN64 S42024-D5013

Siemens S32011-Q125-X-5 BM KO 044726 SCU-R2 S32011-Q125

TERRASAT BUC005865-124-10 BUC005865

Secure Computing SafeWord SecureWire 100 model 220 new

Secure Computing SafeWord SecureWire 2500 525-SYS

INVACOM TUL-204A KU BAND VSAT TX - 2,0 WATT TUL-204

YASKAWA XtraDrive Model XD-50-TN 3 PHASE 16.5 AMPS

Polycom MGC-100 Conferencing Bridge Accord Net-T1 

FUJI ELECTRIC FVR E11 FVRO. 75E11S-4EN 3PHASE O.75KW

TK30 GSM-V3 BOARD GSM 

Alvarion BMax DME CPE SI-E-3.5 735175

Alvarion BreezeACCESS SU-NI-BD-OF OFDM 635303

ATRICA AT80010 SWITCH MANAGEMENT MODULE FOR A-8000

SCHNEIDER KREUZNACH APO COMPONON HM 4/45 MULTICOATING

MAGNETEK SLI-48-230 SLI INVERTER 48V SL48-230

ALVARION AU-RE-LP-2.4 BreezeACCESS 824712

ALVARION E1-SWITCH FOR IDU 500068

ALVARION BreezeMAX PC Card 4M-CPE-PCcard-2.5 725900 NEW

ALVARION BreezeCOM BS-AU-VL CARD AD4276

YASKAWA MAGNETEK GPD205-10P7 VS MINI DRIVER

ALVARION 4M-CPE-ODU-PRO-3.5 ANTENNA 735940

PHILIPS MEDICAL ESD GMBH PCI331 CAN-PCI/331-1

Motorola MVME 340B 01-W3787B BOARD

AUDIOCODES TP-610 TP610A-1205THFU P02 TXBR-48 CPEAX21 

RED ROCK RRT-SPL2038-1 VME W/ SEAGATE HD ST318406W

Berkeley Process Bam-232 Turbo Servo Control

ALVARION/NERA WiLink-CPE-ODU-PRO-SE-3.5 735121N

Schneider AFD PQS lens f=80mm Xenotar 1:2.8 f=80mm HFT 

ANDREW 611678316 KU-BAND TX-RX FEED FOR 123-33.5 HORN

Berkeley Process USA2-11-28-UR MULTI-AXIS SERVO AMP

SIGMA ZOOM-A 1:3.5-4.5 F=35-135mm MULTI COATED LENS

Alvarion RFU-TS 26G 300058 AS0175 NJT7002C4

CORNING TROPEL Optics 141055

SPECTRA PHYSICS LASER MODULE 0129-9535-23

Compaq 153612-006 50/100GB AIT-2 SCSI Tape

VARIAN TV 301 AMAT 7698918 VACUUM PUMP

ZANDAR MVG2 W/MV4 DOGHTER BOARD

EUCHNER SAFETY SWITCH TX3B-A024MC1991

VARIAN TV 301 AMAT SQ424 VACUUM PUMP