Does this overload device also protect short circuits?

[Jpflex]

At my job site we have used older contact overload protection devices for 3 phase motors. We have older systems using original layout:

motor feeder conductor followed by, Motor feed short circuit & ground fault protection, motor disconnect, motor branch circuit short and ground fault protection, motor branch circuit conductor, motor controller, overload protection and finally end to terminate at motor

However, another employee wants to use a different but still older style of protective device which he claims does short circuit ground fault protection and overload protection all in one. There are two dials below unit.

The unit is pictured below. Is this correct for this device?

 

[Jpflex]

Our older starters

 

[Jpflex]

Company won’t buy VFD’s

 

[petersonra]

This appears to be a motor protection circuit breaker. It has both short circuit and OL protection for the motor.

 

[petersonra]

Company won’t buy VFD’s

If what you have is working why would you buy VFDs?

 

[Jpflex]

If what you have is working why would you buy VFDs?

I wrote this in case someone would ask about VFDS.

 

[Jpflex]

This appears to be a motor protection circuit breaker. It has both short circuit and OL protection for the motor.

How do you set both overload protection and short circuit protection on these? Is it done at the two dials below the unit, (ampere adjustment?)

 

[petersonra]

How do you set both overload protection and short circuit protection on these? Is it done at the two dials below the unit, (ampere adjustment?)

Most modern mpcb just have an adjustable overload trip and the short circuit trip is fixed. I can't tell from the grainy picture what the two dials are labeled as.

 

[scrubbin]

The dial on the left is set for “Magnetic-Level” trip
The dial on the right is set for: “Thermal-Level” trip

 

[Jpflex]

The dial on the left is set for “Magnetic-Level” trip
The dial on the right is set for: “Thermal-Level” trip

The setting to the right sounds more like overload thermal setting. The magnetic left side sounds more like short circuit protection?

But if short circuit amperes are preset or not adjustable how do you match OCPD to NEC chart percentage for breakers or overload protection to typical 1.25 percent FLA?

 

[Jpflex]

Ok I thought you were referring to hand dial. Yes I see 2 bottom adjustments. So now what is Big red hand dial For?

 

[scrubbin]

Big red knob is On/Off

 

[petersonra]

The setting to the right sounds more like overload thermal setting. YES

The magnetic left side sounds more like short circuit protection? YES

But if short circuit amperes are preset or not adjustable how do you match OCPD to NEC chart percentage for breakers or overload protection to typical 1.25 percent FLA?

In more modern versions of this, the short circuit trip is preset at 13 X.

 

[augie47]

The two things you picture are not similar critters. The one is a (now obsolete, I believe) Telemecanique manual motor controller without overloads, the second is a SquareD magnetic starter with overloads but without GFSC protection.

​

 

[Jpflex]

In more modern versions of this, the short circuit trip is preset at 13 X.

If preset to 13x full load current preset how does this comply with NEC code chart for breakers and or fuses protecting motors?

 

[jim dungar]

Ok I thought you were referring to hand dial. Yes I see 2 bottom adjustments. So now what is Big red hand dial For?

Manually opening and disconnecting the power contacts. Versions of this device were listed by UL as a Type E combination starter.

 

[petersonra]

If preset to 13x full load current preset how does this comply with NEC code chart for breakers and or fuses protecting motors?

430.52 Rating or Setting for Individual Motor Circuit.
(A) General. The motor branch-circuit short-circuit and
ground-fault protective device shall comply with 430.52(B) and
either 430.52(C) or (D), as applicable.
***
(6) Self-Protected Combination Controller. A listed self protected
combination controller shall be permitted in lieu of
the devices specified in Table 430.52. Adjustable instantaneous trip
settings shall not exceed 1300 percent of full-load motor
current for other than Design B energy-efficient motors and
not more than 1700 percent of full-load motor current for
Design B energy-efficient motors.

According to my math 13005 = 13X.

 

[Tulsa Electrician]

Big red knob is On/Off

And rest after it trips.

 

[milmat1]

You have what is known as an MPCB "motor protection circuit breaker" It has both a short circuit protection (Mag Trip) and thermal overload protection..(usually adjustable)

Do not confuse it with the MCP which is just an instantaneous trip circuit breaker.