These values can be obtained from the motor specifications. MCM uses these values to determine
whether the motor complies with its specifications and incorrect values are likely to raise alarms.
Frequency:
If motor is driven with VFD, it must be set RPM according to frequency of VFD. For 4 pole motors
(1500 rpm); if motor is running on 40 Hz, RPM is set 1200 rpm. The nominal line frequency (or most
commonly expected frequency in the case of an inverter) should also be set.
𝐴𝑐𝑡𝑢𝑎𝑙 𝑟𝑝𝑚 =
𝑛𝑜𝑚𝑖𝑛𝑎𝑙 𝑟𝑝𝑚 𝑥 𝑎𝑐𝑡𝑢𝑎𝑙 𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦
𝑛𝑜𝑚𝑖𝑛𝑎𝑙 𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦
VT Ratio:
eMCM voltage input terminals support up to 690Vrms. Voltage transformers should be used at
voltages of 690Vrms and above. Voltage transformer conversion rate information can be obtained
from VT’s datasheet.
• 6600V/110V, PT Ratio: 60
• 7200V/100V, PT Ratio: 72
CT Ratio:
The eMCM device has two models that support 3.5mA (eMCM 5A) and 100mA (eMCM 100A)
current input.
• For motors with nominal current of 10A and below, eMCM 5A device should be used
together with current transformers with 3.5mA secondary current output. In this context,
there are 3 current transformers with different primary current inputs. The conversion rates
of these current transformers are as follows:
o 3.5A/3.5mA, CT Ratio:1
o 7A/3.5mA, CT Ratio:2
o 10A/3.5mA, CT Ratio:3
• For motors with nominal current over 10A, eMCM 100A device should be used together
with current transformers with 100mA secondary current output. The conversion rates of
these current transformers are as follows:
o 100A/100mA, CT Ratio: 1
o 200A/100mA, CT Ratio: 2
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