APM 2.8 Auto Disarming

my APM is auto Disarming.after some time wen i rise and down the throttle…

If you arm the motors and do not raise the throttle within 15 seconds, the APM will automatically disarm the motors. If you arm the motors, raise throttle, lower throttle and leave the motors at idle for 15 seconds, APM will automatically disarm the motors.

Dear

if i leave my throttle to 60 percent and my quad is in the air than after 15 second if AOM is disarmed than the quad may be crashed … so why this feature is in apn it is unfair and dangrous . because some time we keep our throttle to an specific percent and leave it ther but if it disarme after 15 sec of same throttle than its dangrous…

No, you misunderstand. APM will disarm if the throttle is at IDLE or FULL LOW STICK.

Tell me EXACTLY and in DETAIL what it is you are trying to accomplish…

I am using APM 2.8 with three Simonk (30A, 5v, 2A ESC BEC) and one mystery (5v 3A ESC BEC) and let me tell you that i am powering my APM using ESC (with jp1 connected) i am not using Power Module.
my problem is that my APM is taking so many try of pattern (throttle at min and than bottom left) to Arm . and once it is armed Red LED become solid on APM. but as i rise my throttle up all motors start spinning and every thing is looking normal but suddenly APM disarmed why this is happning. APM should disarm after throttle low and than bottom left. tell me whats the problem may be the problem in my parameteres because apm is arming after so many try. if it disarm during flight than my quadcopter may be crash. i am sending you picture of my parameteres and TX may be you find some thing wrong.

and the socond issue let me know that is it okay to use diffrent brand esc in one quadcopter because i am feeling that the esc which is powering my APM is getting little bit hot when motor spin in armed i am using three Simonk 30A (5v 2A) with one mystry 30A (5v 3A)
current is diffrent in one of my esc . and i am powering with one of my simonk esc so is it possible that diffrence in current can make our esc hot…waiting for your reply

Part of the problem is the radio. Having to do the pattern multiple times means that for some reason the radio is not sending valid signals. With radios like this stick trim can be an issue. I would try centering all of the stick trims and re-calibrating the radio.

Another thing I would do is use ESCs that are the same brand and use a power module. You could be having an issue with the +5 volts from the ESCs being noisy and this is particularly problematic with ESCs that have switching BECs.

Finally, you need to learn how to download and use data flash logs…
http://ardupilot.org/copter/docs/common-diagnosing-problems-using-logs.html