Technical FAQs

Ask a Question

Does thermal overload protection (49RMS) in SEPAM series 20/40/60/80 in motor protection models inhibit the start order of the motor?

Sepam is showing Start Inhibit warning when ANSI 66 is not the source for the warning.

Product Line:
Sepam 20, 40, 80


Sepam is blocking equipment start with Start Inhibit but ANSI 66 is not the protection causing the warning.

It is possible for the thermal overload protection (49RMS) inhibit the motor start. During each motor start, thermal heating/ increment of start is computed and is registered in SEPAM. After the motor start, no matter if the relay is tripped by 49RMS or it’s done manually by operators, the relay will do a simple verification. If the existing thermal level of the motor in addition to registered thermal increment dedicated to last start becomes bigger than Es2 then SEPAM will inhibit the motor start.

The existing thermal level of motor is reported in SEPAM and can be viewed by connecting to the relay and going to Network diagnosis> Machine in SFT2841. It is reported as “Thermal capacity used”.

To show how SEPAM verify the start inhibition we name it as “M”. Thermal heating/ increment of each motor start is not reported by relay but is saved in a register in SEPAM. Let’s name it as “N”. Es2 is heat rise tripping set point. So SEPAM will check below condition in order to decide to inhibit or not inhibit the closing order. If this condition becomes valid the start order would be inhibited.
M+N > Es2

The message on the SEPAM would be “start inhibit”, which is also grouped with 66(start per hour) protection.
Was this helpful?
What can we do to improve the information ?