DOLD 0060947 – MH9143.39 +/-5Hz UH AC230V | JUAL DOLD 0060947 – MH9143.39 +/-5Hz UH AC230V – Mains Frequency Monitor MH 9143 | Relay modules > Monitoring devices > Measuring relays / Monitoring relays > Measuring relays for main monitoring > MH 9143 > Mains Frequency Monitor > Mains Frequency Monitor MH 9143 > MH9143.39 +/-5Hz UH AC230V