Basic Installation and Operation Guide VMX Series Digital Solid State Soft Starters 18 – 1000A
Page 25 of 27
Chapter 5 - Motor Overload Protection
Solid State Overload Protection
The
VMX Series
Starter provides true U.L. listed I
2
t Thermal Overload Protection as a built-in function of the
main digital processor for maximum motor protection. It simulates the tripping action of a bi-metallic overload
relay, with the accuracy and repeatability of a digital control system. It is adjustable over a wide range and can
be easily programmed for different trip curves.
Thermal Memory
The
VMX Series
microprocessor uses a sophisticated “Thermal Register” in the digital memory to keep track of
motor heating and cooling over time regardless of the starter’s power status. By using non-volatile memory, the
VMX Series
does not “forget” that the motor has been running even if power to the starter is turned off and back
on. Continuous overload protection is provided based on the true thermal condition of the motor.
Thermal Capacity
The Thermal Register is displayed as a percentage. This percentage is the motor’s remaining thermal capacity.
The percentage value begins at 100, showing that the motor is cool (has 100% of its capacity available). As the
motor heats up or moves toward an overload condition, the percentage begins to drop. The Thermal Capacity is
derived from the programmed motor nameplate Full Load Amps (FLA) in Function F001, the Service Factor
rating in Function F002, and the Overload Trip Class in Functions F003 and F004. Setting these functions to the
proper values provides maximum protection and eliminates nuisance tripping.
The Remaining Thermal Capacity can be viewed by using the UP or DOWN
arrow keys when in the Status Display mode. From the default Phase A
Current screen (dot on right side), press the UP arrow key 4 times to display
[H100]
meaning there is 100% of the Thermal Capacity (H = Heat capacity)
remaining in the motor. After starting or running, the motor will use this capacity
and the display will show a lower number. For example, after a cold start, the
display may read
[H065]
which indicates that the motor has 65% of its thermal
capacity remaining (35% used). The Status Display screens cycle back to the
beginning, so the Down arrow keys can get to this display as well.
Motor Full Load (FLA) Setting
Use Function F001 to enter motor FLA as indicated on the motor nameplate.
(Do not calculate for service factor, this is programmed separately in F002).
Note:
All
VMX Series
starters are shipped from the factory with F001 set to a default value of 0000. If
F001 is left at the factory default, the unit will not operate. If the user attempts to start the
VMX
Series
without entering the motor nameplate FLA, the starter
will Fault and the display will read
“
nFLA
” (no Full Load Amps).
Disabling the Overload Protection
The Overload Protection feature can be disabled if necessary. Please refer to the Advanced Installation,
Operation and Programming Manual for instructions and considerations before disabling the Overload
Protection
WARNING!
Do NOT disable Overload Protection unless another Thermal Overload Protection device
exists in the circuit for all three phases. Running a motor without Overload Protection
presents serious risk of motor damage or fire.
H057
H 100
100% Thermal Capacity
remaining at rest
Examples:
57% Thermal Capacity
remaining after starting
(43% used)
Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: [email protected]
