100122-1140 EST
My Fluke 27 has a maximum of 1000 V DC. My Simpson 270 (260) has a 1000 V range with - to + terminals and 5000 V with - to DC 5000 V terminals. I also have a 30,000 V probe to the Simpson.
Then I have a home made compensated 30,000 V plus probe, actually a Bud box, to oscilloscope input. This was made in the 50s when I was working on the development of improved automotive ignition systems.
For low frequency DC measurements you can simply add series resistance to a Simpson meter to increase its input voltage capability. You have to be careful when playing with high voltages. Means you need to know what you are doing.
A Simpson 260 is basically a 50 microamp full scale meter. One volt at 50 microamps is 1/0.000,05 = 20,000 ohms. Thus it is defined as a 20,000 ohms per volt meter. To turn this 50 microamp meter into a voltmeter you add series resistance at the rate of 20,000 ohms for each full scale volt you desire. At the 1000 V range the Simpson looks like 20,000,000 ohms. Higher than a Fluke 27. If you want to make the Simpson into 2,500 V full scale meter, then you need a total resistance of 20,000 * 2,500 = 50,000,000 ohms. If you use the 1000 V range, then you need to add 30,000,000 ohms external. Since the Simpson has a 2.5 range it means you can directly read from the scale without any multiplying factor.
Note the Simpson has a 5000 ohms/volt sensitivity on AC, and older ones were 1000 ohms/volt.
.
