How to safe measure DC voltage up 150V

[BlueG]

Hello,

I would like to measure DC voltage up to 150V. It is easy to measure the DC voltage through resistive divider (see page 11 in https://tinycontrol.pl/media/documents/m...008_EN.pdf), but I do not know How to make a protection. Can you suggest me something which make the circuit safe from overvoltage ? Actually the primary circuit is protected by DC power surge protector DS240S-130DC from overvoltage so it may be sufficient, but I have no experience with that - is it needed/useful to have second protection ?

I suppose that you like to measure PV installation. We made special sensor for it, it is even added to analog inputs as HV DC meter. Its special Hall effect device with big resitors to measure up 500V and with good separation between high voltage and output section. Unfortunately after some tests in summer it was broken after light storm (not near). Lan Controller was OK.  
It is difficult to say how react your surge protector (how fast is), but usually PV charger or inverter has on inputs elements with high voltage parameter, so very short stress few times higher as normal parameters can be accepted. Resistor divider not protect from this spikes but you can try protect it by transil diodes. We use this type of diodes on Lan Controller board (for about 56V) but I saw also for much higher voltages. BUT STILL YOU HAVE TO REMEMBER THAT HIGH VOLTAGE (NOT OVERVOLTAGE) CAN APPEAR ON LAN CONTROLLER AND 150V  IS DANGEROUS.
In my opinion few kV separation like this HV DC voltage Hall effect sensor is much safer.

Thank you. You are right, I would like to measure PV installation. Is it possible to buy this HV DC meter with hall effect ?