T200 User's Manual SECTION 6: T200 FUNCTIONAL OVERVIEW
PAGE 6-62
The T200 measures the motor phase currents at a high frequency. Approximately 2 times per second, a new RMS
current limit is calculated. The algorithm measures the RMS phase current for the last averaging period. It calculates
the remaining amount of current for the next 0.5 seconds, for which the total current over the averaging period would be
20Arms. This remainder becomes the RMS current limit for the next 0.5second period.
The RMS current over the last averaging period is made available to the user. The "?LMR" command lists the actual
RMS current value via the Hand Held Terminal interface.
6.9.5 Regeneration Resistor Protection Scheme
The regeneration function dissipates energy that is returned to the T200 from a decelerating load or from a counteracting
torque. Regenerative energy dumping is handled by thermal dissipation through conduction of current through
regeneration resistors. There are two resistive regeneration mechanisms in the T200:-
1. Internal Regeneration Resistor:- The T200 has an internal regeneration resistor which provides a 40W
continuous/2.8kW peak dissipation capability. The internal regeneration resistor is protected by an Electronic
Circuit Breaker. The breaker will inhibit the conduction of current in the internal regeneration resistor if the
continuous conduction capability of the resistor is exceeded. In an application where high levels of regenerative
power are fed back into the mains, an external regeneration resistor is needed. When the ratings of the internal
regeneration resistor are exceeded, the Electronic Circuit Breaker will inhibit further conduction in the internal
resistor. This will leave the external resistor to handle dissipation of further regenerative energy.
2. External Regeneration Resistor:- The conduction of the external regeneration resistor is monitored in order to
detect if its continuous rating has been exceeded. Note that the THRM_LIM Thermal Limit Active output of
the T200 will activate if the external regeneration resistor's ratings have been exceeded.
Due to the possible variations in connecting the power section of T200’s (see section 3.10, 3.11) the functionality for
indication that the max. continuous regen power is exceeded can be adapted to the needs of the users application.
The following drive reactions can be selected:
• Regen Exceeded disabled
There will be no reaction of the T200 if the calculated continuous regen power exceeds the max. continuous regen
power of the selected regen resistor.
This is especially necessary in applications where the DC-Bus of T200’s with internal PSU is paralleled. In such a
configuration only one T200-X10 will have an external regen resistor attached. As the calculated regen energy is
based on the assumption that an external regen resistor is connected the calculated regen energy of all drives without
an external regeneration resistor is wrong and the warnings are misleading.
CAUTION:- The user's application should monitor for the activation of the
THRM_LIM Thermal_Limit_Active digital output, and take action to reduce or remove
further thermal stress on the T200, regeneration resistors and motor. If action is not
taken then the external regeneration resistor may be damaged, or the fuse may be blown
WARNING:- It is the users responsibility to ensure that the Regen Exceeded
functionality is only switched off when no external regen resistor is used for this T200.
There is no other indication that the cont. regen power is exceeded. Exceeding
continuous regen power will damage the regen resistor and can cause the resistor to
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