About the M9M04PA002.000
Equipping the MM300 series relays with a residual ground input, a Modbus RTU RS485 port, a thermistor input, and a 50:0.025 CBCT input, the M9M04PA002.000 is a CPU module produced by General Electric Multilin. The CPU module is contained in slot B of the relay, and comes with an optional communications board that provides Ethernet and Fieldbus ports. The MM300 series itself is a line of Motor Management Relays that serve low voltage motor systems.
Buyers can connect either a negative temperature coefficient (NTC) or positive temperature coefficient (PTC) to the + and - terminals on the CPU module. The MM300 is able to automatically assess whether the thermistor type is NTC or PTC, reducing the amount of work necessary on the end of the user. Buyers should employ thermistors that have hot and cold resistance values in a range of 100 to 30,000 ohms. Note that in the event that no thermistor is connected to the CPU module, “Thermistor Trip” and “Thermistor Alarm” settings must be disabled.
The RS485 port provided by the M9M04PA002.000 is two-wire. A maximum of thirty-two MM300 IEDs may be daisy-chained together on a comms channel, or else the driver capability will be exceeded. Additional serial channels can be added for larger systems that require more than thirty-two MM300 IEDs. The RS485 terminals also all feature surge protection devices due to the fact that voltage differences between remote ends of the communication link may occur. Noise coupling is also prevented by an isolated power supply with an octocoupled data interface.
