信号源指电流电压信号的各种逻辑组合，也就是一个信号源包含所在测量特定电力设备中的负荷或故障量时需要的信号。一个给定的源可能包括以下信号：三相电流，单相接地电流，三相电压和用来检同期的由单个 VT 提供的附加电压。

VICKERS DG4V-3S-2AL-M-F?TWL-H5-60 HYDRAULIC VALVE WITH S

YAMATAKE HONEYWELL KIX19B-E12X2SY-?XSX SMART ELETROMAGN

AEG 160A CIRCUIT BREAKER MCbs 160 IN BOX

ABB ASEA 110-120V COIL 110A CONTINUOUS RATING CONTACTOR

MICHIGAN CUTTING TOOL TD-000217 / MCT-100092 BORING BAR

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ALLEN BRADLEY 120V COIL MANUAL MOTOR CONTROLLER 140-MN-

KEBA 10-SLOT CONTROL RACK KERMO-BUS-8

FUJI ELECTRIC 100-110V COIL 26A MAGNETIC CONTACTOR 4NC0

INDRAMAT CONTROL BOARD PCB APR 4-02/00

ABB SACE S5 2-POLE 400A CIRCUIT BREAKER S5H M-1248 SACE

ALLEN BRADLEY 0.37KW/0.5HP PRESET SPEED CONTROLLER 160-

PARKER SCHRADER BELLOWS 24 VDC SOLENOID PNEUMATIC VALVE

ROSS 2768C4904 PNEUMATIC CHECK VALVE

SYLVANIA QTP3X32T8/UNV PSN-SC 120-277V 3-LAMP ELECTRONI