multiple speed detective relay

[PAW 0]

Hello, We have a multiple speed detective relay: terminals: 2-7 dc supply voltage 24v 4-5 AC input 2v~300v 1-3 H (NO) 6-8 L (NO) The set revolutions for H is 2070 rpm and 450 rpm for L, as far as I understand it H and L will be ON if it reaches the set value respectively. This will be detected on the ac input (4-5). The dials for H and L are mark from 0 to 10. Are the dials for H and L represents the percent setting of the set value? How does it exactly operates? Actually this device was installed on the automatic control panel of the genset to detect the speed of the the genset. I tried contact the supplier of the genset but I got no reply from them. The brand name of the device is IIZUKA DENKI SEIKUSHO CO., however I could not find the site. Maybe somebody here can help me. Thanks in advance, Paw