Motor differential protection 87M

Description

Overview

• The motor differential protection device adopts professional differential motor protection logic. It is an integrated protection and control unit developed for high- and low-voltage asynchronous motors, available for standalone panel installation or built-in mounting in switchgear cabinets.

Product Functions (ANSI)

• Differential Instantaneous Overcurrent Protection (ANSI 87)
• Percentage Bias Differential Protection (ANSI 87M)
• Stage 1 Instantaneous Overcurrent Protection (ANSI 50)
• Stage 2 Definite Time Overcurrent Protection (ANSI 51)
• Stage 3 Definite Time Overcurrent Protection (ANSI 51)
• Inverse Time Overcurrent Protection (ANSI 51)
• Overload Protection (ANSI 49)
• Thermal Overload Protection (ANSI 49)
• Locked Rotor Protection (ANSI 48)
• Long Start-up Time Protection (ANSI 48)
• Motor Start Blocking
• Stage 1 Negative Sequence Overcurrent Protection (ANSI 46)
• Stage 2 Negative Sequence Overcurrent Protection (ANSI 46)
• Negative Sequence Inverse Time Overcurrent Protection (ANSI 46)
• Zero Sequence Overcurrent Protection (ANSI 50N / 51N)
• Overvoltage Protection (ANSI 59)
• Undervoltage Protection (ANSI 27)
• Zero Sequence Overvoltage Protection (ANSI 59N)
• Overfrequency Protection (ANSI 81O)
• Underfrequency Protection (ANSI 81U)
• PT Circuit Break Detection (ANSI 60)
• PT Voltage Loss Protection (ANSI 60)
• Control Circuit Break Alarm
• System Power Loss Alarm
• Non-electrical Protection

Measurement and Control Functions

• Category	No.	Parameter	Specification
  Electrical Measurement Parameters	1	Bus Voltage	Ua, Ub, Uc, Uab, Ubc, Uca
  	2	Measured Current	Ia, Ic
  	3	Power	Active Power P, Reactive Power Q, Power Factor COSφ
  	4	Frequency	f
  	5	Electric Energy	EP+, EP-, EQ+, EQ-
  Binary Input	6	Active Binary Input Channels	21 channels; input voltage options: AC/DC 220V, DC 100V, DC 48V (to be specified when ordering)
  Binary Output	7	Protection Output Channels	11 channels
  	8	Signal Output Channels	2 channels
  	9	Closing Position Signal Output Channel	1 channel
  	10	Device Power Loss Output Channel	1 channel

Communication Functions

Item	Description
Communication Interfaces	1 × Ethernet port 2 × RS-485 ports (the second RS-485 port shares the time synchronization port; function selectable via configuration)
Communication Protocols	IEC 60870-5-103, IEC 61850 (Ethernet), MODBUS RTU
Time Synchronization	Communication message synchronization, SNTP, IRIG-B

Setting Table of Motor differential protection

No.	Setting Name	Setting Range	Unit	Default Value	Remarks
1	Differential Starting Current Setting	0.1~100	A	1
2	Differential Instantaneous Overcurrent Setting	0.1~100	A	5
3	Inflection Point Setting	0.1~100	A	1
4	Percentage Bias Coefficient	0.1~0.9	—	0.5
5	Motor Rated Current	0.1~100	A	5
6	Motor Starting Time	0～600	S	5
7	Stage I Overcurrent Setting	0.1~100	A	8
8	Stage II Overcurrent Setting	0.1~100	A	7
9	Stage II Overcurrent Time Delay	0～100	S	0.5
10	Stage III Overcurrent Setting	0.1~100	A	5
11	Stage III Overcurrent Time Delay	0～100	S	1
12	Inverse Time Overcurrent Setting	0.1~100	A	5
13	Inverse Time Overcurrent Delay	0～100	S	1
14	Inverse Time Overcurrent Type	0~3	—	1	1=Normal, 2=Very, 3=Extreme
15	Overload Setting	0.1~100	A	5
16	Overload Time Delay	0～100	S	2
17	Overload Protection Type	0~2	—	1	0=Disabled, 1=Trip, 2=Alarm
18	Locked Rotor Protection Setting	0.1~100	A	2
19	Locked Rotor Protection Delay	0～100	S	1
20	Negative Sequence Stage I Overcurrent Setting	0.1~100	A	2
21	Negative Sequence Stage I Overcurrent Delay	0～100	S	1
22	Negative Sequence Stage II Overcurrent Setting	0.1~100	A	1
23	Negative Sequence Stage II Overcurrent Delay	0～100	S	2
24	Negative Sequence Stage II Protection Type	0~2	—	1	0=Disabled, 1=Trip, 2=Alarm
25	Zero Sequence Overcurrent Setting	0.1~100	A	2
26	Zero Sequence Overcurrent Time Delay	0～100	S	2
27	Zero Sequence Overcurrent Protection Type	0~2	—	1	0=Disabled, 1=Trip, 2=Alarm
28	Negative Sequence Current Thermal Coefficient	2~10	—	6	Default: 6
29	Thermal Time Constant	0.01~100	min	5
30	Heat Dissipation Time Constant	1~5	Times	5	Normally 1~5 times of thermal time constant
31	Overheating Alarm Level	10%~100%	—	80%
32	Long Starting Time Setting	0.1～100	A	5
33	Long Starting Time Enable Duration	0～100	S	3
34	Start Interval Time Setting	0～100	min	10
35	Undervoltage Block Starting Setting	1～400	V	70
36	Overvoltage Setting	1～600	V	120
37	Overvoltage Time Delay	0～100	S	0.5
38	Undervoltage Setting	1～400	V	80
39	Undervoltage Time Delay	0～100	S	1
40	Zero Sequence Overvoltage Setting	1～400	V	30
41	Zero Sequence Overvoltage Time Delay	0～100	S	0.5
42	Zero Sequence Overvoltage Protection Type	0~2	—	1	0=Disabled, 1=Trip, 2=Alarm
43	Overfrequency Setting	35～60	Hz	49
44	Overfrequency Time Delay	0～100	S	0.5
45	Underfrequency Protection Setting	35.0～65	Hz	51
46	Underfrequency Time Delay	0～100	S	0.5
47	Undervoltage Block Frequency Setting	1～400	V	20
48	Slip Block Frequency Setting	1～30	Hz/S	3
49	PT Circuit Break Time Delay	0～100	S	5
50	PT Voltage Loss Time Delay	0～100	S	5
51	Control Circuit Break Time Delay	0～100	S	10
52	System Power Loss Type	0~2	—	1	0=Disabled, 1=Trip, 2=Alarm
53	High Temperature Alarm Delay	0～100	S	0.1
54	High Temperature Trip Delay	0～100	S	0.1
55	Non-electrical Protection 1 Type	0～2	—	1	0=Disabled, 1=Trip, 2=Alarm
56	Non-electrical Protection 1 Time Delay	0～100	S	0.1
57	Non-electrical Protection 2 Type	0～2	—	1	0=Disabled, 1=Trip, 2=Alarm
58	Non-electrical Protection 2 Time Delay	0～100	S	0.1

Outline and Installation Dimensions

   

FAQ

Q：What types of motors require differential protection?

A:motor differential protection scheme

Motors of 2000 kW and above shall be equipped with differential protection. For motors below 2000 kW, differential protection is required if instantaneous current protection lacks sufficient sensitivity.

High-voltage motors for critical special applications (such as mine main drives and main ventilation) must be fitted with differential protection to ensure safe, reliable operation and avoid major losses and incidents.

Critical six-lead motors below 2000 kW shall also use differential protection as main protection for internal short circuits, when instantaneous protection cannot meet sensitivity requirements.

Q：What is the CT wiring configuration for motor differential protection?

For standard motors, the polarity end of CT (T/P marked terminal) must face the busbar or transformer side to ensure correct secondary current direction.

In motor differential protection CT connection, the wiring of differential protection of motor shall strictly follow A-A, B-B and C-C phase matching.

For units adopting motor differential protection self balancing, it is required to configure motor differential protection core balance CT and zero-sequence balance CT; please refer to the official wiring diagram for specific connection methods.

Q: ANSI code for motor differential protection?

A: ANSI standard code is 87M.

Q: Main protected faults?

A: Stator phase short-circuit, winding earth fault and inter-turn short circuit.