2) Reducing the dis turbance to th e in ver ter fro m o the r equ ipme nt
The re lay, co ntactor or ele ctro nic -magnetic br aking dev ice wil l disturb t he inve rte r.
Tak e the following actions to solve this issue:
A) Ins tall surge sup pre ssing d evices to th e disturbing devic e
B) Ins tall filter t o the input of the inverter
C) Inv erte r's contro l ca bles shall be shie lde d a nd t he shielding layer shal l be gro unded
3) Met hod to redu ce the di sturbance from the i nve rter to the equip ment
Two k inds of noises , one is the ra diation from the inverte r it self, and a nother is the radiation from the
cable b etwee n the in ve rter and th e moto r. T hes e tw o k inds of ra diations induce the cables of th e
equ ipm en t and mak e th e equipme nt work a bno rmally. Follo wing m ethod can be use d:
A) If the mea sur ing me ters , ra dio equipment and sens ors and th eir signal cab les are installed in a
cabine t together with th e drive, thes e equip me nt c ables w ill be eas ily disturb ed. Take the actions
below to s olve the p roblem: The equipment and th e signal cable s s hou ld be a s far aw ay fro m the
inverter as possible; Si gna l ca ble s and power cabl es shall not be ro ute d in pa ral lel o r boun d together;
The signa l and p ower c ables should b e shie lde d; Install radio noise filter and lin ear noise filter a t
the input and output sides of the inve rte r
B) If the e xterna l equ ipme nt shar es a same AC supply wi th t he inve rte r, a nd the above cannot eliminate
the dis turban ce, the n the u ser should install a line ar filte r or a radio no ise filter.
C) Ground th e ex ter nal equ ipment an d e limina te the disturb ance of the le aka ge cur rent fro m t he
inverter's grounding ca ble .
The in ver ter has two ki nds of leakag e curre nt, one is the gro unding lea kage c urrent and anoth er is the
lea kage curre nt betw ee n the lines :
1) Grou nd ing leakage c urr ent:
The distributed capacitanc e exist s between the cables an d the g rou nd, and the bigger the c apa citanc e
and the bigger th e le akage curren t, s o th e moto r ca ble s should b e a s sh ort as pos sible. B esides , the
bigg er the ca rrier frequenc y is, the b igger the leakage cu rrent i s, so the us er c an also re duc e the c arr ier
wa ve f requency, but the motor noise ma y incre ase . In sta lling re actor c an also re duc e the leakage curren t.
The le aka ge cur rent is increas ed wit h th e incre ase of the circuit curren t, so the l eakage curren t is big if
the motor power is big.
2) Lea kage curre nt betw ee n lines:
The distributed capacitanc e exist s in the inver ter
抯
o utput cables, and re son anc e may occur if high
fre que ncy ha rmo nic s e xist in the curren t, thus the lea kage c urre nt occu rs , which may result in the wrong
action of rela y.
The method to so lve this issue is to r edu ce the car rier fre que ncy or install the output re actor. I t is
rec ommende d to us e in ver ter
抯
protection fun ction i nst ead of a th ermal rela y to pro te ct the motor before
using the inv erte r.
6.3 Le aka ge cur rent
-15-
-1 6-
Note:
Pay attention to the polarity of the dio de as shown in the figur e 3-8. Othe rwise if the digita l
output terminal has output, the DC24V pow er supply w ill be dama ged.
6. EMC Issue s
6 1 Influence of Harmonics
6. 2 EM I
1) The h igh frequency ha rmoni cs of m ains supply will influe nce the rectifying circuit of t he inverter.
The harmonic s will heat t he rec tifying circ uit and ev en dama ge th e circuit. So, it is recommended to
install the filt ering devic e in the envi ronment where the pow er qua lity i s poor.
Since the in verte r output has hig h freque ncy harmonics, the output cannot be ins talled with
ca pacitor or surge s uppre ssing devic es bec ause the cap acitor and s urge suppre ssing devic e may
re sonate the c ircuit and damage the e quipment.
1) Two kinds of EM I, one is the EMI around the inverter and distu rbs the inve rter. T his kind of E MI is
w eak, besides the in verte r has been designed with strong immunity. Another i s the E MI from the
inverter that m ay influence the equipment around the inverte r. The inve rter its elf is a disturbance
source b ecaus e it outputs PWM wave through high carrier frequency, so solving the EMI issue is
mainly to reduce the EMI of inverter.
M ethods:
A ) Inve rter an d oth er equipment shall be w ell grounde d and the gr ounding res istanc e sha ll be le ss tha n
5ohm.
B ) Inve rter's p ower cable s shall be ve rtical inste ad of paralle l with the c ontrol cable s.
C ) For the app lication with strong dis turba nce, the pow er ca bles from the motor to the inverter shall b e
shielded and the shi elding laye r shall be gr ounde d.
D ) The c ables of disturbe d equi pment shall be tw isted shielded ca bles and the shiel ding la yer s hall be
gr ounde d.
.
2)
DZB300
EV
MO 1
MC M
Relay
Diode
Fig. 3 -8 Digital Input Ter minal of DZ B Ser ies Inverter
Chapter 3 M echanic al and Electrical Instal lation
DZB Series
C hapter 3 Mechani cal and Electr ical Insta llation
DZB Series
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