**NEW** BACS Current Sensor - Generation 5

04 May 2023

Higher precision - DIN rail mounting AND “flexible” mounting -
with differential current measurement - with 8cm diameter -

Current sensors are used with the SENSORMANAGER and BACS for the measurement and data acquisition of DC and AC currents. Current values are important for the detection of battery faults, unbalanced strings, UPS or charger faults and for battery capacity measurements.

Improved Measurement Precision:

With Generation 5, our Current Sensors have seen a noted increase in measurement precision as compared to the preceeding Generations 3 and 4. With Generation 5, the resolution -- especially in the low range (trickle charge) -- has been improved significantly, and thus also the measurement result of BACS’ battery capacity functionality.

From left to right: The current sensors of Generation 3, 4 and 5: While the 3rd Generation sensor (on the far left) still had a “closed” ring through which the cables had to be pulled, Generation 4 (middle picture) introduced the “open” ring concept. With Generation 5 (right picture), the sensor is “flexible” and can be installed on a DIN rail as well as freely in the cable harness if desired.

New Mounting Variants:

In addition, a new mounting variant is added to the program with the 5th Generation. In addition to the still-available DIN rail mounting CSHxxxx, an "F" flexible mounting variant has been added to the program:
The CHSxxxF is ideal for a "hanging" position, allowing for free mounting in cramped conditions. Often, power cables are laid in such a way that a DIN rail cannot be mounted. Previously this would mean that the CSHxxxx with DIN rail would hang freely in the air, which is technically no problem, but visually it “leaves something to be desired”...

Sometimes the cables do not fit through the sensor hole when the sensor sits horizontally or vertically on a DIN rail, or if the cables are routed in such a way that there is no space for the DIN housing. This problem can be solved with the CSHxxxxF by hanging the sensor like a current clamp in a more suitable location within the installation.

Left picture: Sensor of Generation 5 - This sensor CSHxxx is mounted on a DIN rail.
Middle and right picture: Sensor of Generation 5 - This CSHxxxxF sensor can do both - mounting via a DIN rail (optional) or free-hanging.

Simple Application, New-Install or Retrofit:

A BACS system wouldn’t inherantly require current sensors if a UPS connection via COM 1 or via network (SNMP RFC 1628) is available. In such cases, the basic detection of a power failure can be carried out and reported by the UPS itself, and not by a given current sensor. However, if the customer wants to have battery capacity and/or thermal runaway detection, then current sensors will need to be retrofitted for each battery string.

Generation 4 und Generation 5 Sensors: The CSHxxx/F/D sensors are all equipped with hinged technology and are therefore very easy to install.

This is possible with all CS sensors featuring "H" in the product name. All CSH sensors are “openable” via hinge; this hinge technology allows the sensors to be retrofitted at any time without system interruption, which naturally makes for a much simpler and straightforward installation as compared to the previous “pull through” method, which required disconnection of any associated cables. However, this hinge method previously came at the expense of accuracy, so we have developed Generation 5, which now measures even more accurately than even the closed sensor of Generation 3.

Larger Transducer Diameter of 8cm:

The CSHxxxxF is also available in a variant with a larger transducer diameter: All variants of the CSxxxx and CSHxxxx current sensors were previously available with a maximum diameter of 40mm. This is sufficient for all common power cables in the EU, but in the USA and Asia, cable diameters even thicker than 4cm can sometimes be found, for example within power plants. Therefore we now offer a special version of the current sensor with 8cm diameter:

CSH1000F8 with Transducer allowing cables with up to 80mm diameter

For BACS as well as for SENSORMANAGER:

All sensors of the 4th Generation and 5th Generation can be used either for the SENSORMANAGER or for BACS. For BACS the right side with the BACS bus sockets RJ10 is used, for the SENSORMANAGER the left side with RJ12 sockets.

Differential Current Input:

All sensors of the 5th Generation have the possibility to connect the differential current sensor CSHxxxxD in order to detect possible leakages between DC input and DC output.

Residual currents ought by all means be avoided in DC equipment as they can be potentially dangerous – these currents move along a non-linear path, and could cause electrocution if touched. The chance of a fatal electric shock depends on numerous factors, but this problem should be recognized and corrected to prevent injury and personal damage.

Generally live parts of electrical appliances are protected with a personal protection / residual current circuit breaker, but this is not the case with UPS systems! Depending on the specific system, there may be no residual current circuit breaker in use, so that a "leakage" can quickly lead to personal injury. The usual "workarounds" by means of an insulated battery pack etc. provide safety, but because of the potential danger of a leakage current this can lead not only to personal injury, but also to property damage - it is paramount to know immediately if and when such a condition exists. Leakage currents are harmful to the batteries and endanger the UPS technology, and can lead to a fire. For this reason, the use of residual current sensors is required in many tenders in the USA and by the US authority NERC.

The new CSHxxxF current sensor can be used with the CSHxxxD for the detection and measurement of differential currents.

For this, the CSHxxxF is installed in the positive line of the DC bank and the CSHxxxD in the negative line. A communication cable is laid between the two sensors as shown in the picture:
As soon as a difference between input (CSHxxxF) and output (CSHxxxD) is detected, the BACS Webmanager raises an alarm and warns of a potentially life-threatening situation on site.

In addition, the Ground Fault Detection provides valuable information about the quality of the current flow, and indicates that losses occur in a monitored segment, which negatively affect the performance of the overall system and potentially pose a fire hazard.

Picture: CSH1000D (left) with connection cable to a CSH1000F (right)

Simple equation, big effect:
„What goes in must come out": Both sensors are connected via “daisy chain” and then connected to a BACS WEBMANAGER. The WEBMANAGER can decide immediately on the basis of the available measurement data if there is an occlusion or similar deviations, and trigger an alarm according to its configuration.