Loadside residual current devices Basic RCD320 and Basic RCD520
Loadside residual current devices are also available to order for 3VA1 molded case circuit breakers.
Description of front panel view
"Ready" signals and alarms
"Ready" signal of the residual current device:
The LED labeled "ACT" stands for ACTIVE and lights up when the device is ready to operate.
Both the Basic RCD320 and the Basic RCD520 feature an alarm LED labeled "AL" (pre-alarm) which lights up promptly to indicate potential shutdown of the installation due to residual current.
The <RESET> button is not only used to reset the residual current device, but also as a mechanical indication that the unit has "tripped". If a residual current is detected or the button <TEST> is pressed, the button <RESET> is automatically released and so signals that the residual current device has tripped. Even when the residual current device is at zero potential, the <RESET> remains in the "TRIP" position.
It is absolutely essential to isolate the evaluation electronics circuit while insulation tests are in progress in order to protect the circuit against potential damage on the one hand and to prevent detection of insulation faults due to the power pack on the other. This is done simply by withdrawing (15 - 17 mm) the circuit breaker which is anchored in the enclosure.
Disconnection of the main conductor connections is thus unnecessary. On completion of the tests, the circuit breaker must be pushed back into position before the residual current device is commissioned.
Testing and resetting the residual current device
Depending on operating conditions, the test button on the front panel of the residual current device should be pressed in order to function-test the device. The test button is labeled with the letter "T". If the test button is pressed, the device is tested immediately irrespective of the current delay time setting.
If the test button is pressed, a residual current is simulated on a test winding attached to the summation current transformer. If the residual current device is functioning properly, it must trip the molded case circuit breaker.
The test button must be held down for at least 2 seconds. The design of the test button prevents unintentional actuation.
If the residual current device trips the molded case circuit breaker due to a high residual current or actuation of the test button, the <RESET> button on the RCD is released. At the same time, the trip alarm switch which is mechanically coupled with the <RESET> button also signals that a trip has occurred.
The <RESET> button is labeled with the letter "R".
The following actions must be taken in order to reset the residual current device and reclose the main contacts of the molded case circuit breaker:
Press the <RESET> button on the residual current device.
The "tripped" signal at the signaling contacts is canceled, the residual current device is now reset.
Reset and switch on the molded case circuit breaker.
Parameterization of the residual current device
Button for setting the response current IΔn
The response current can be set in 8 steps, ranging from 0.03 A to maximum 5 A. Each response current has a dedicated setting range. The corresponding response current is set as soon as the button is latched in the setting range.
If the white setting arrow is resting between two setting ranges, the residual current device is automatically set to 0.03 A for safety reasons.
If the response current is set to 0.03 A, the delay time setting is deactivated and the breaker is tripped instantaneously in order to afford personal protection in the case of direct contact.
The factory setting for the response current is 0.03 A.
Button for setting the delay time Δt (RCD520 only)
The delay time on the RCD520 residual current device can be set in 8 steps, ranging from 0 (instantaneous) to a maximum value of 3000 ms.
Each delay time has a dedicated setting range. The corresponding delay time is set as soon as the button is latched in the setting range.
If the white setting arrow is resting between two setting ranges, the residual current device trips instantaneously in response to residual currents.
The factory setting for the tripping delay is 0 ms.
The delay time is not adjustable on the RCD320. The RCD320 always trips instantaneously.
Recommended procedure for setting the response current and the delay time
Switch off the molded case circuit breaker.
Open the transparent protective cover over the setting buttons.
Adjust the setting values for response current and delay time on the residual current device to the maximum value in each case.
Switch on the molded case circuit breaker.
The LED labeled "ACT" on the residual current device now lights up, the residual current device is ready.
Reduce the setting for the response current until the LED labeled "AL" lights up.
The residual current is now 30% higher than the response current setting.
By turning the setting button clockwise, set the next higher response current.
The LED "AL" goes out, the correct response current is now set.
Set the required delay time.
Close the transparent protective cover over the setting buttons.
The device is now fully parameterized.
Sealable protective covers of the residual current device
Transparent protective cover over setting buttons
In order to prevent unauthorized access to the setting buttons for IΔn and Δt, the transparent cover over the settings buttons can be optionally sealed.
Contact hazard protective cover over main current paths and auxiliary contacts including sealing option
After the residual current device RCD320 or RCD520 has been mounted on the 3VA1 molded case circuit breaker, a contact hazard protective cover is installed over the main current paths to protect against direct contact. This cover can be sealed optionally in order to block any attempt to dismantle the residual current device from the molded case circuit breaker.
A number of auxiliary contacts which perform different functions are located underneath the contact hazard protective cover:
TRIP-IND (TRIP INDICATOR)
A tripped signal can be output via the floating contact for display via a warning lamp, for example. This trip alarm switch operates as soon as the residual current exceeds the response current setting value and has therefore caused the residual current device to trip.
The standard trip alarm switch has changeover contacts and screw-type connections.
The terminal designations of the relevant contact are shown in the diagram below.
The table below illustrates the behavior of pre-alarm and tripped signals on RCD320 or RCD520 units in response to various user actions and residual currents.
Cable ducts for bringing out cables are provided to the left and right on the residual current device.
Other labels on front panel
The residual current device bears the CE mark. For an overview of all approvals, please refer to Appendix.
For all queries relating to approvals, please contact Technical Support.
In ≤ ...A:
Specifies the highest permissible rated operational current of the molded case circuit breaker with which the residual current device may be combined.
Ue ∼ ...V:
Specifies the operating voltage range of the residual current device.
Specifies the operating frequency range of the residual current device.
Denotes the response behavior to residual currents.
Regardless of the type of connection system installed on the 3VA1 molded case circuit breaker, the residual current devices RCD320 and RCD520 are mounted on the load side (i.e. beneath the thermal-magnetic trip unit) of the breaker:
Dismantle the loadside connection components of the molded case circuit breaker and install the supplied connection components for the residual current device.
Insert the residual current device into the T slots of the molded case circuit breaker.
Push the residual current device backwards until its rear panel is flush with the rear panel of the molded case circuit breaker.
Screw the molded case circuit breaker to the residual current device. Special connecting screws are provided on the line side of the residual current device for this purpose.
Place a contact hazard protective cover over the circuit breaker/RCD assembly.
Reinstall the loadside connection components of the molded case circuit breaker at the outgoing feeder end of the residual current device.
Attach the assembly to a mounting plate using the fastening screws.
The molded case circuit breaker is tripped by means of a direct-acting tappet which engages in the breaker mechanism from the residual current device. The electromagnetic trip unit is integrated in the residual current device.
The table below provides an overview of all the functions and data which are available in the residual current device environment: