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ISM-200  DC Insulation Monitor

Monitor of AC & DC voltage

  • MCM will display voltage between busbars and ground including 

negative busbar to ground and positive to ground. It also

measures voltage for AC signal interruption.

  • When system voltage is higher or lower than setting threshold in

DC system malfunction, or when AC voltage exceeds setting v

value, warning info will be sent out with LED indicator and buzzer.

  • Warning info can be sent to automation system via YX switching

value and RS485 connector.

Insulation Monitor

  • MCM will in real time monitor and display grounding resistance between busbars positive and negative) and ground.

  • When system voltage of positive-ground and negative-ground is unbalanced, and unbalanced value exceeds setting value, there will be warning info.

Grounding Detection

  • The MCM will receive monitored data from DAMs in real time and analyze the grounding status of each branch circuit. It could accurately calculate grounding resistance and precisely judge which branch has ground fault, if any. During this process, it smartly bypasses the interferences from charger pulse, fluctuation of electrical level and so on.

  • Grounding resistance will display on LCD screen and could be transfer to integrated automation system via RS485

Current diagnosis

  • There is current sensor on each DAM, and the measured current values are transferred to the MCM. This will help technicians know comprehensive status of the DC system and quickly eliminate malfunction timely.

Early warning for insulation problems

  • The MCM has high accurate measurement up to 500K. It will monitor the long time trending for the grounding resistance between circuit and ground. This tendency of resistance changes will supply early warning before a ground fault happens. It will be very helpful for a preventative maintenance.

History record play back

  • AC signal interference and grounding record will be automatically saved in EEPROM. This record will include time of AC interference & grounding, grounding resistance, interference voltage, grounding circuit and so on.

  • It records up to 1000 events.

Voltage balance

  • When ratio of voltage values (positive busbar to ground and negative busbar to ground) exceeds protection index of 1.222, this system will use compensation bridge to balance the voltage values of both busbar to ground. In another word, the ratio of positive ground voltage and negative-ground voltage will become higher than 0.869. Or the ratio of negative-ground voltage and positive-ground voltage will be lower than 1.150.

Battery circuit monitor

  • This monitoring system will monitor insulation/grounding status of battery circuit in real time with the help of data recorder and current clamps.

Measurement of distributed capacitance

  • It can measure values distributed capacitance for the tested DC system.

Key Features:
  • State-of-art designing with industrial chip and components.

  • Overall processing capability is dynamically adjustable based on branch circuits (DAM).

  • Maximally it supports dozens of CPU working at the same time.

  • This system adopts unique DADC framework. This makes it flexible for onsite commission and system expansion.

  • Digital signal enhancement technology:

  • User friendly interface with easy going instruction on screen.

  • It uses DC current sensor for detection of current leakage without injecting any external signal.

  • Anti-interference designing using both software and hardware ensures the stable operation for long time even in strong interference environment.

System Architecture:

There are 2 ways of connection between MCM and DAM:

   1. Each DAM can connect directly with MCM via SynBus.

   2. Each DAM can connect with another DAM nearby via their HUB 

       connectors and then to MCM. Communication between each DAM is

       decided by their unique IP code instead of physical position. This

       makes it flexible for installation onsite.

Both MCM and DAM are with hot plugging. MCM can automatically identify DAM without manual setting.

Each DAM can connect with up to 8 CTs. When CT is connected with DAM, DAM will automatically identify each CT without manual setting.

System Composition:

The whole system is composed of 3 essential components: the Main Control Machine (MCM), Data Acquisition Module (DAM) and DC Current Sensor (CT).






Power supply:



Control Machine (MCM)

It is the control unit of the whole system.

It is also the interface for data display and

parameter setting.

MCM is fixed on power supply panel.

85-300V from AC mains or DC



Data Acquisition Module (DAM)

Monitor current status for the circuits that

are connected.

DAM unit is connected between MCM

and CT with flexible installation location.

12V, powered by MCM

17*11.2*2.5 cm


DC Current Sensor (CT)

Monitor current status for each circuit.

CT is connected at outlet circuit of each

DC power supply.

10mA, 20mA & 100mA








Power supply:










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