Questions

A1. Difficult to give a precise answer because it depends on what contact you make, a tight grip with wet hands could probably be dangerous with as low as 24vac. 60v ac could certainly be dangerous. I'm sure others will offer alternate views.

A2. I dunno.

A3. Depends what the full load is! A permanent magnet DC motor will do...but these are generally fairly low power. Others will have experience of higher power stuff.

1. Depends. How old is your pacemaker? Are you sitting in salt water? Voltage doesn't kill you; current does. The general rule of thumb is that 5 mA through the heart is fatal. That is the supposed cutoff for GFI breakers. There is a general notion that 50V is safe, and that is reflected in some codes. HOWEVER, if you've ever been hit with the old fashioned ring voltage while standing in wet grass, you will have your suspicions about that. I personally do not deliberately touch anything higher than 12.6VAC

2. 1 ton = 12000 BTU/hr

3. No one correct answer. There are any number of techniques for high starting torque.

Tom

1. Why can't you research your own homework answers instead of asking strangers to do it for you? One of the best lessons to learn in school is in how to find answers on your own, employers will not want to pay you for clicking through internet forums, they could do that themselves.

2. Do you not know how to use Google or other search engines? I suggest you learn.

3. A motor that has been properly engineered for your application. That is why people become engineers instead of purchasing agents.

1. I agree with Del

2. Your question doesn't make sense. What kind of refrigerant? And then it probably all comes down to how and at what rate you use the refrigerant.

3. The best motor for starting under maximum load is probably the series type DC motor used for traction applications. This motor is so strong that it is capable of shearing shafts if obstructed when pulling away. That is of course only possible if supplied from an adequate power source.

It has the added property that, if run with no load, it will keep accelerating until it flies apart. It is therefore usually only connected to the load by positive means like gears and such.

Many motors are designed to have an increased torque concentrated higher or lower along the speed curve, much like the power band of a car's engine. For the right application, you just have to ask the manufacturer.

And, don't be put off by a grumpy, ill mannered 'know it all' forumite who was probably born with all lots of knowledge and very little manners. Some of these guys give the impression they only read the forum in order to find someone to pick on.

I suggest you get some assistance in formulating your questions but don't stop asking.

1 . The first question is not properly stated . I think it is better to put like this

what is the safe value of ac current to pass over a human body ?

Answer

The effects of electric shock are

1 to 5 mA - Discernible but no danger

5 mA - 15 mA - Pain experienced and muscular contraction which can repel the person

20 mA - 50 mA - Impossible to release grasp ,extreme pain and loss of consciousness

50 mA - 75 mA - Paralysis with no pulse or respiration

Greater the than 100 mA

Ventricullar fibrillation causing death