214 A. M. Alekseev et a I. 



of VNII Geofizika, A. M. Alexeev, N. A. Bulanov and others, designed 

 two new electrical exploration stations, one of which--ERST-23-56 — is 

 intended for working in inaccessible country and also in the winter (the 

 so-called tractor variant); the second — the EPS-16-56— a cross -covnitry 

 dismountable, is only for dipole probing in inaccessible country. 



The following are the basic features of the new stations which will indicate 

 the possibilities of their use in other problems of surveying under various 

 conditions. 



The ERST -23-56 station is mounted on a trailer and its two PN-100 genera- 

 tors are powered by a special gasoline engine ZlS-120, the gear box shaft 

 of which is connected by a universal joint to the shaft of the first generator 

 (Fig. 14). The engine and generators are mounted on shock absorbers and 

 since they are connected by a universal joint during operations the power 

 unit does not cause vibration in the body or measuring apparatus. 



To control the engine, on the control desk there is a special panel which 

 has: a gasoline level indicator, an ammeter to check the operation of the 

 charging generator, an oil manometer included in the lubrication system of 

 the engine, a thermometer to check the cooling system of the engine. Also 

 on the control desk there are buttons for controlling the gas and the air 

 intake, a starter button, and also a clutch pedal and gear shift. 



With a booster arrangement, the voltage of the two connected generators 

 can be increased to 1000 V providing the resistance of the insulation 

 of the current leads is not less than 5 MQ. 



The new station has benefited from the experience of the ERS-23-53 

 stations which are used by the electrical exploration parties. In the station 

 there is a fixed loading resistance, which can be used as a ballast loading 

 to use when operating with the usual arrangement, since in a number of 

 regions in measurements with the doubling arrangement there is distortion 

 in the rectangular nature of the current impulses. 



Apart from the EPO-5 oscillograph, an extra apparatus is provided to 

 measure A U. Under winter conditions, considerable difficulties are expe- 

 rienced in earthing; the station therefore has a d.c. amjDlifier with an 

 input resistance of the order of several megohms; this makes it possible to 

 carry out measurements of AU in regions with poor earthing conditions of 

 MN, where the intermediate resistance can reach very high values (of the 

 order of 50-100 x 10=^^). 



In the tractor variant of the station, the generator group and all the measur- 

 ing apparatus are placed on a trailer with caterpillars, which is drawai by 

 an S-80 tractor. On the trailer there is a metal body suitable for operation 

 under winter conditions. Between the two walls of the body there is a heat 



