Carlyle multiple reciprocating compressor systems/ low oil alarm in Carrier chiller

[Hamooody]

Hello Dear Friends,
I have a refurbish carrier chiller type 30HT.
After I started up the chiller both systems A and B sounds an alarm 50 and 51 " Low oil pressure compressor A1 lead comp. in sys. A and B1 lead comp. in sys. B. (Note the compressors have oil equalizer pipe in each system).
I added a required oil to both systems and then less an hour all the oil in sys. A "four comp." and sys. B "three comp." disappeared completely.
Now I am confused !!
What happened and what should I do?
Even if one compressor in work also drag the oil from the rests.
Is it compressor's o-ring or vales problem?
I'm waiting your kind help my friends.
http://www.hosbv.com/data/specifications/3258%20-%20Carrier%2030%20HW%20052.pdf

[Magoo]

Did you have crankcase oil heaters operating for at least 24 hours before starting compressor?

[Hamooody]

Hi Magoo,
Thanks to you.
Of course we have crankcase heaters, but not operating always because we have shortage in electricity and have programmed cutting about 6 hours a day. And our ambient temperature is 39 centigrade.
Now why the oil not coming back to comp. case? 3GS oil is light or easy-moving.
I thought also that in working time the oil pump pressure is not higher than suction pressure at least 12- 35 psi. but why have this situation in both systems?

Did you have crankcase oil heaters operating for at least 24 hours before starting compressor?