TCI HGA Manual - Manual (Page 51)

51
Overload / Over Current Protected
The filter has factory set built-in electronic overload and over current protection. If the converter
current exceeds the preset instantaneous peak, the converter will shut down to prevent permanent
damage to the converter, and at which time it will indicate a fault. Faults that do not automatically
reset can be cleared by pressing the stop button on the HMI display.
An indication that the filter is going into overload will be observed by a gradual worsening of the
total harmonic distortion (THD), or power factor, as the load increases. The HGA filter units can
be paralleled to increase total corrective current capability if a unit is undersized for a particular
application. Call TCI sales support for options to expand the installed system current capability.
Circuit Breaker Protection
Each converter section is protected by a thermo magnetic circuit breaker; in the event the HGA
experiences a catastrophic failure, or a destructive over current condition should occur. It also
provides a convenient disconnect means to isolate the converter from the power source. The size
and type of circuit breaker must not be altered without consulting TCI engineering since the circuit
breaker is an integral part of the UL file.
Notes:
• Open chassis units can be provided without circuit breakers. The end user must protect the
HGA with the following UL listed thermal magnetic common trip molded case circuit
breaker.
• 39, 45, 78 & 50 Amp: A max peak let-through current of 26 kA in correspondence with a
short circuit of 100 kA at 480 volt, and a trip current of 100 amps.
• 90 to 100 Amp: A max peak let-through current of 26 kA in correspondence with a short
circuit of 100 kA at 480 volt, and a trip current of 125 amps.
• 200 Amp: A max peak let-through current of 35 kA in correspondence with a short circuit
of 100 kA at 480 volt, and a trip current of 225 amps.
Warning
If the system breaker has been tripped, do not attempt to re-energize the HGA unit. Until the
cause of the trip has been determined.
Pre-Charge Circuit Over Current Protection
SCR’s are used to limit the converter power up in-rush current to a safe level once the converter
DC voltage has reached the threshold, SCRS will be turned on and the charging resistor will
be cut off from the unit. If for some reason this circuitry should malfunction, class CC fuses are
in the circuit to limit the max current as not to exceed the ratings of the components. Note: on the
50 to 100 amp units the fuses are located on the chassis; on the 175 and 225 amp units the fuses
are located on the interface/mother printed circuit board.
Over Temperature Protection
The converter has a thermal fold back mechanism that will automatically reduce unit output
current as the converter temperature approaches its shutdown threshold. Additionally, the
converter has an internal heat sink over temperature protection which will shut down the converter
if the threshold is exceeded. The fans will continue to run and once the heat sink cools down the
converter will automatically restart.
There are secondary over temperature circuits which monitor the temperature of the power
resistors and inductors located on the chassis of the HGA. The sensors are snap action switches
activated when the threshold is reached. This over temp would be an indication that cooling fans
!