We professional manufacture OEM of frequency meter Our company past Certificate of CE and ISO9001; frequency meter Product Specification:JYX-45-HZ Frequency ... not be connected wronging,or it will be burn the meter.3.The voltage signal can be input directly if it ... ,above 500V should concect the current transformerXXX/100V.4.Frequency meter , sampling AC voltage signal input value,(110V-380V), i.e ...