Contax 6521 SO static, single-phase, classs 1 active power meter that measures the power consumption for a determined installation.
Characteristics:
  Two modules wide
  Opto-isolated pulse output
  Five-digit plus 1 decimal place without zeroing
Measurements:  35mmW x 88mmH x 66mmD
Voltage rating 230V a.c.   50-60Hz, operating voltage 195V to 253V
Ib current (max) 10 (65) A,  operating current 0.04A to 65A
Start-up current with power factor 1:  40mA typical
Own consumption 7.5VA (0.8w) approx
Precision class 1
Pulse retransmission type SO
Recorded harmonics up to 7kHz
Operating limit temperature:  -20